`IdentifierHiding`: Improve performance, address some false positives/false negatives #3253

Job	Run time
Prepare CodeQL unit test matrix	11s
Run unit tests (cpp, 2.18.4, codeql-cli/v2.18.4, codeql-bundle-v2.18.4, ubuntu-latest-xl, codeql-...	20m 36s
Run unit tests (c, 2.18.4, codeql-cli/v2.18.4, codeql-bundle-v2.18.4, ubuntu-latest-xl, codeql-cl...	18m 21s
Validate test results	4s
	39m 12s

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