Revert "Add synchronized lock for ringback playing start/stop request to avoid" am: a485ff8e

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/services/Telecomm/+/22359847



Change-Id: Ia6ce4fd2dd6243226b21863e6ca2cb6addd8183b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>