SoundTriggerService.startRecognition - callingUser

SoundTriggerService.startRecognitionForService() uses the calling user
for setting up its RemoteSoundTriggerDetectionService, to inform the
caller of sound trigger events.

However, this method is first clearing the calling id, so when it
fetches the caller's userHandle, it will always get user 0, rather than
the actual caller.

This cl fixes that.

Bug: 341193639
Test: Manual - have an app in user 10 use this service and verify it receives the triggers
Flag: EXEMPT bugfix
Change-Id: I5bcec1797f65d53ff6110241ddd827c2dc4bf894