AudioRecord: Enforce worker thread join in dtor

Ensure that the AudioRecordThread is joined in dtor. In some
cases if the dtor was called while the worker thread was in
restoreRecord_l() (which had an error due to audioserver restart)
the mStatus check incorrectly prevented join.

Test: atest CtsMediaAudioTestCases
Test: Camera video record and killing audioserver
Test: atest test_callback_race
Bug: 331329042
Change-Id: I2d16e716d8b5945762bc0cfd0b278c5c00ca8f80