Remove use of UserHandle in LocationTimeZoneEvent

It causes problems with permissions in testing and isn't strictly
required so it can be removed.

Bug: 152744911
Bug: 149014708
Test: atest services/tests/servicestests/src/android/location/timezone/LocationTimeZoneEventTest.java
Change-Id: Iba9c07780e3cc9f94f2c77144c48916236f31e60