TST: Replace ensure_clean_store with tmp_path in test_timezones.py

[Chiwendaiyue]

This PR replaces the usage of ensure_clean_store with the pytest tmp_path fixture in pandas/tests/io/pytables/test_timezones.py, as part of the ongoing effort to migrate away from the ensure_clean utility function.
Changes Made

• Replaced all instances of ensure_clean_store(setup_path) with tmp_path fixture
• Used pd.HDFStore(path) with unique filenames for each test to avoid conflicts
• Removed the import of ensure_clean_store from the file
• All tests continue to pass with the new implementation

Technical Details

• Created unique HDF5 filenames for each test using tmp_path / "test_name.h5"
• Maintained all existing test logic and assertions
• Follows the project's guidance for replacing ensure_clean with pytest fixtures

Testing

• All 71 tests in test_timezones.py pass
• 1 test skipped (unrelated to changes)
• No regressions introduced

Related Issue
Addresses the migration from ensure_clean to temp_file/tmp_path #fixtures62435