Ensure ST does not remain requested after error

After an error, since the service notifies the client, the service
should not attempt to restart recognition again when a state update
occurs, otherwise a state mismatch will occur.

Also, null out the recog token when the model state is cleared.

Bug: 272147641
Fixes: 280911900
Test: AlwaysOnHotwordDetectorTest#
    testRecognitionNotRequested_afterResumeFailed
Change-Id: I3f7c441a87292d767b6296d6075218a29850da2c