Clear mPendingAudioProcessingCall

Clear mPendingAudioProcessingCall in CallsManager when the call gets set
to active for the first time so that it doesn't get reused when the call
potentially comes off hold later on.

Fixes: 159743938
Test: atest BackgroundCallAudioTest
Change-Id: Ibbf06a46620fd31e83c1a29044cc11b6997faa18
1 file changed