AudioTrack and AudioRecord: add stopAndJoinCallbacks()

Explicitly force callbacks to stop running.
This is needed to prevent a race condition with
the callbacks running after a close.

Bug: 164411271
Bug: 143305727
Bug: 182954108
Test: atest CtsNativeMediaAAudioTestCases
Test: libaaudio/tests/test_callback_race.cpp
Change-Id: Ia86c758d7f1c281a5d933bc384283440e1f1a756