Add test API for Telecomm cts testing

The Ringer CTS test cannot access the @hide API
under android/media/Utils.

Add TestAPi annotation for following:
-. VIBRATION_URI_PARAM
-. SYNCHRONIZED_VIBRATION

Flag: EXEMPT TEST_ONLY
Bug: 394231980
Test: presubmit
Change-Id: Iaf32e3fb530f800260f5a8ca98b708c88655e424