Add tracing log, variance in periodic job runs

This change also add tracing tag, add variance
in job interval to avoid both db writing at
the same time, and adding some more unit tests.

Bug: 377584611
Test: atest com.android.server.appop.DiscreteOpsMigrationAndRollbackTest
Test: atest com.android.server.appop.DiscreteAppOpSqlPersistenceTest
Test: atest com.android.server.appop.DiscreteAppOpXmlPersistenceTest
Test: atest com.android.server.appop.AppOpHistoryHelperTest
Flag: android.permission.flags.enable_all_sqlite_appops_accesses
Change-Id: I728ae4abae2ff04c5d8906db79a6c68818c57aee