Fix NumObjects and Initialized with WriteTxn

[joamaki]

Both NumObjects() and Initialized() returned the committed state and not the currently modified state:

txn := db.WriteTxn(tbl)
tbl.NumObjects(txn) == 0
tbl.Insert(txn, Foo{})
tbl.NumObjects(txn) == 0 !!!

init := tbl.RegisterInitializer("test")
tbl.Initialized(txn) == false

init(txn)
tbl.Initialized(txn) == false !!!

[github-actions]

$ make test
go: downloading github.com/mitchellh/mapstructure v1.5.0
go: downloading golang.org/x/term v0.16.0
go: downloading github.com/spf13/cast v1.6.0
go: downloading github.com/fsnotify/fsnotify v1.7.0
go: downloading github.com/sagikazarmark/slog-shim v0.1.0
go: downloading github.com/spf13/afero v1.11.0
go: downloading golang.org/x/sys v0.17.0
go: downloading github.com/subosito/gotenv v1.6.0
go: downloading github.com/hashicorp/hcl v1.0.0
go: downloading gopkg.in/ini.v1 v1.67.0
go: downloading github.com/magiconair/properties v1.8.7
go: downloading github.com/pelletier/go-toml/v2 v2.1.0
go: downloading golang.org/x/text v0.14.0
	github.com/cilium/statedb/reconciler/benchmark		coverage: 0.0% of statements
	github.com/cilium/statedb/reconciler/example		coverage: 0.0% of statements
ok  	github.com/cilium/statedb	5.264s	coverage: 88.8% of statements
ok  	github.com/cilium/statedb/index	0.006s	coverage: 25.5% of statements
ok  	github.com/cilium/statedb/internal	0.008s	coverage: 93.3% of statements
ok  	github.com/cilium/statedb/part	1.788s	coverage: 82.5% of statements
ok  	github.com/cilium/statedb/reconciler	2.297s	coverage: 92.0% of statements
-----
$ make bench
go test ./... -bench . -benchmem -test.run xxx
goos: linux
goarch: amd64
pkg: github.com/cilium/statedb
cpu: AMD EPYC 7763 64-Core Processor                
BenchmarkDB_WriteTxn_1-4                    	  448350	      2568 ns/op	    389355 objects/sec	    2720 B/op	      32 allocs/op
BenchmarkDB_WriteTxn_10-4                   	 1248512	       953.7 ns/op	   1048525 objects/sec	     715 B/op	      10 allocs/op
BenchmarkDB_WriteTxn_100-4                  	 1601576	       778.9 ns/op	   1283832 objects/sec	     582 B/op	       7 allocs/op
BenchmarkDB_WriteTxn_1000-4                 	 1524307	       785.4 ns/op	   1273158 objects/sec	     533 B/op	       7 allocs/op
BenchmarkDB_WriteTxn_10000-4                	 1263010	       985.0 ns/op	   1015264 objects/sec	     554 B/op	       7 allocs/op
BenchmarkDB_WriteTxn_100_SecondaryIndex-4   	  535526	      2263 ns/op	    441874 objects/sec	    1671 B/op	      30 allocs/op
BenchmarkDB_RandomInsert-4                  	    2416	    479935 ns/op	   2083615 objects/sec	  386103 B/op	    7100 allocs/op
BenchmarkDB_RandomReplace-4                 	     427	   2802489 ns/op	    356826 objects/sec	 1847344 B/op	   30564 allocs/op
BenchmarkDB_SequentialInsert-4              	    1562	    783347 ns/op	   1276574 objects/sec	  533720 B/op	    7288 allocs/op
BenchmarkDB_Changes_Baseline-4              	    1256	    947163 ns/op	   1055786 objects/sec	  536188 B/op	   10246 allocs/op
BenchmarkDB_Changes-4                       	     702	   1706062 ns/op	    586145 objects/sec	  964342 B/op	   14541 allocs/op
BenchmarkDB_RandomLookup-4                  	   20188	     57240 ns/op	  17470545 objects/sec	     144 B/op	       1 allocs/op
BenchmarkDB_SequentialLookup-4              	   24882	     47292 ns/op	  21145392 objects/sec	       0 B/op	       0 allocs/op
BenchmarkDB_FullIteration_All-4             	     813	   1450652 ns/op	  68934630 objects/sec	     360 B/op	       7 allocs/op
BenchmarkDB_FullIteration_Get-4             	     207	   7648686 ns/op	  13074162 objects/sec	       0 B/op	       0 allocs/op
BenchmarkDB_PropagationDelay-4              	  494841	      2251 ns/op	        20.00 50th_µs	        22.00 90th_µs	        94.00 99th_µs	    1514 B/op	      24 allocs/op
PASS
ok  	github.com/cilium/statedb	26.481s
PASS
ok  	github.com/cilium/statedb/index	0.004s
PASS
ok  	github.com/cilium/statedb/internal	0.003s
goos: linux
goarch: amd64
pkg: github.com/cilium/statedb/part
cpu: AMD EPYC 7763 64-Core Processor                
Benchmark_Insert_RootOnlyWatch-4    	    9786	    121790 ns/op	   8210886 objects/sec	  104118 B/op	    2041 allocs/op
Benchmark_Insert-4                  	    6427	    170851 ns/op	   5853038 objects/sec	  202681 B/op	    3064 allocs/op
Benchmark_Replace-4                 	29615572	        40.59 ns/op	  24634151 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Replace_RootOnlyWatch-4   	29527713	        40.59 ns/op	  24638268 objects/sec	       0 B/op	       0 allocs/op
Benchmark_txn_1-4                   	 2972832	       396.3 ns/op	   2523385 objects/sec	     432 B/op	       7 allocs/op
Benchmark_txn_10-4                  	 7793312	       151.9 ns/op	   6585318 objects/sec	     152 B/op	       2 allocs/op
Benchmark_txn_100-4                 	 7508161	       173.9 ns/op	   5750672 objects/sec	     223 B/op	       2 allocs/op
Benchmark_txn_1000-4                	 7668471	       152.7 ns/op	   6547189 objects/sec	     215 B/op	       2 allocs/op
Benchmark_txn_10000-4               	 5412721	       226.6 ns/op	   4413570 objects/sec	     237 B/op	       2 allocs/op
Benchmark_txn_100000-4              	 4325589	       286.8 ns/op	   3487321 objects/sec	     343 B/op	       2 allocs/op
Benchmark_txn_delete_1-4            	 3235819	       367.5 ns/op	   2721019 objects/sec	     840 B/op	       6 allocs/op
Benchmark_txn_delete_10-4           	 8671322	       135.5 ns/op	   7381561 objects/sec	     131 B/op	       1 allocs/op
Benchmark_txn_delete_100-4          	10564479	       110.5 ns/op	   9050374 objects/sec	      60 B/op	       1 allocs/op
Benchmark_txn_delete_1000-4         	12047515	        99.21 ns/op	  10079253 objects/sec	      26 B/op	       1 allocs/op
Benchmark_txn_delete_10000-4        	10159572	       116.8 ns/op	   8558873 objects/sec	      25 B/op	       1 allocs/op
Benchmark_txn_delete_100000-4       	 9182602	       130.4 ns/op	   7669181 objects/sec	      26 B/op	       1 allocs/op
Benchmark_Get-4                     	   38839	     30478 ns/op	  32810339 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Iterate-4                 	  166304	      7338 ns/op	 136277490 objects/sec	      80 B/op	       3 allocs/op
Benchmark_Hashmap_Insert-4          	   15562	     77354 ns/op	  12927599 objects/sec	   86556 B/op	      64 allocs/op
Benchmark_Hashmap_Get_Uint64-4      	  156871	      7809 ns/op	 128055308 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Hashmap_Get_Bytes-4       	  153370	      7772 ns/op	 128669252 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Uint64Map_Random-4        	    1260	    930516 ns/op	   1074673 items/sec	 2689528 B/op	    9025 allocs/op
Benchmark_Uint64Map_Sequential-4    	    1436	    872737 ns/op	   1145822 items/sec	 2476394 B/op	    9749 allocs/op
PASS
ok  	github.com/cilium/statedb/part	32.697s
PASS
ok  	github.com/cilium/statedb/reconciler	0.004s
?   	github.com/cilium/statedb/reconciler/benchmark	[no test files]
?   	github.com/cilium/statedb/reconciler/example	[no test files]
go run ./reconciler/benchmark -quiet
1000000 objects reconciled in 2.83 seconds (batch size 1000)
Throughput 353266.44 objects per second
Allocated 6011435 objects, 409095kB bytes, 535024kB bytes still in use