Remove voiceinteraction identity fabrication

VoiceInteractionManagerService uses its own identity instead of its
clients when attaching to the SoundTrigger stack to prevent appop
attribution if an event is actually delivered.

Now that ST has a notion of a trusted client, remove this special
handling, and pass the real client identity.

Attach as trusted middleman.

Bug: 272147641
Fixes: 278626726
Test: AlwaysOnHotwordDetectorTest
Test: Manual verification of hotword, now playing
Change-Id: I4cfc57af0ead5a21baadc3f328551c0011b3c38b