Refactor `RemoveDuplicatedCaseInSwitchRector` and adding test cases #29991

Job	Run time
Composer Validate	22s
Help and Version	24s
Preload php-parser Order	18s
PHPStan	1m 15s
Commented Code	17s
Compatible PHPStan versions	15s
Run with Space in Directory	21s
Active Classes	28s
Check before/after test fixture on no-changes	19s
Detect composer dependency issues	26s
Check no "*.php" files in rules Fixture directory	14s
Finalize classes	25s
	5m 4s

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