Move long-running test out of CTS

The test is long-running and checks behavior that is not user or SDK
API-facing. The flag is unlikely to be used / not intended for use by
partners, so the test can be moved outside CTS.

Test: atest core/tests/coretests/src/android/app/time/TimeManagerTest.java
Bug: 275470097
Change-Id: I9ee5ec6712e0b413e41337e4aad74ac0af72f0c6