Remove SoundTriggerService stopping state

Essentially reverts f3e7be00

The addition of this state caused several state mismatch issues, and
spurious error callbacks.

Removing, and solving the underlying race condition in a subsequent
commit.

Bug: 236826280
Bug: 268217943
Fixes: 275079746
Test: AlwaysOnHotwordDetectorTest#
    testAbortRecognitionAndOnResourceAvailable_recognitionPausedAndResumed
Test: CtsSoundTriggerTestCases
Test: CtsVoiceInteractionTestCases
Test: Manual verification
Change-Id: Icedc330c9fefbe6444dfec886672a97d603098e4