Fix logic for rust-analyzer.checkOnSave.features setting inheritance #5347

Job	Run time
test (ubuntu-latest, 27.2, false)	4m 44s
test (ubuntu-latest, 28.2, false)	4m 43s
test (ubuntu-latest, 29.4, false)	5m 4s
test (macos-latest, 28.2, false)	3m 42s
test (macos-latest, 29.4, false)	3m 50s
test (windows-latest, 27.2, false)	3m 6s
test (windows-latest, 28.2, false)	3m 32s
test (windows-latest, 29.4, false)	5m 5s
test (ubuntu-latest, snapshot, true)	3m 31s
test (macos-latest, snapshot, true)	2m 47s
test (windows-latest, snapshot, true)	2m 55s
	42m 59s

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