refactor(cubesql): Fix clippy warnings in cubesql, part 2

[mcheshkov]

Check List

• Tests have been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Description of Changes Made (if issue reference is not provided)

Just a bunch of small clippy fixes around the codebase, targeted to enable more rules

[codecov]

Codecov Report

Attention: Patch coverage is 29.34363% with 366 lines in your changes missing coverage. Please review.

Project coverage is 83.64%. Comparing base (e12dc44) to head (87123c5).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...sql/cubesql/src/compile/rewrite/rules/old_split.rs	0.00%	321 Missing ⚠️
.../cubesql/src/compile/engine/df/optimizers/utils.rs	8.69%	21 Missing ⚠️
rust/cubesql/cubesql/src/compile/engine/df/scan.rs	21.42%	11 Missing ⚠️
...besql/cubesql/src/compile/rewrite/rules/members.rs	76.47%	4 Missing ⚠️
rust/cubesql/cubesql/src/compile/plan.rs	0.00%	3 Missing ⚠️
...t/cubesql/cubesql/src/compile/engine/df/wrapper.rs	90.00%	1 Missing ⚠️
...t/cubesql/cubesql/src/compile/rewrite/converter.rs	95.65%	1 Missing ⚠️
...st/cubesql/cubesql/src/compile/rewrite/rewriter.rs	0.00%	1 Missing ⚠️
rust/cubesql/cubesql/src/sql/postgres/extended.rs	75.00%	1 Missing ⚠️
rust/cubesql/cubesql/src/sql/postgres/shim.rs	80.00%	1 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9262      +/-   ##
==========================================
+ Coverage   83.57%   83.64%   +0.06%     
==========================================
  Files         227      227              
  Lines       81652    81576      -76     
==========================================
- Hits        68242    68234       -8     
+ Misses      13410    13342      -68     

Flag	Coverage Δ
cubesql	83.64% <29.34%> (+0.06%)	⬆️

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[KSDaemon]

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