LPS-50131 Create unit test for TimeZoneUtil
LPS-50131 This does not need NewClassLoaderJUnitTestRunner
LPS-50131 Should use assertNotSame()
LPS-50131 Should highlight out TimeZoneUtil.getTimeZone() is cache while TimeZone.getTimeZone() is not.
LPS-50131 Simplify test logic
LPS-50131 Rename methods
LPS-50131 Restore the previous default timezone after test
LPS-50131 SF