Added logic to reset assistant UIDs on audio crash

On native audioserver recovery the assistant UIDs will reset to an empty
list, followed by adding the current role or setting holder for
assistant. Also added a settings lock around the update assistant
method. Added remove assistant UID for reset hotword detection
connection.

Bug: 222584963
Bug: 222777782
Test: atest VoiceInteractionTest
Test: atest AudioManagerTest
Test: atest HotwordDetectionServiceBasicTest
Test: kill audio server and verify assistant UIDs is not increasing
	unbounded.
Test: adb shell cmd voiceinteraction restart-detection, verify assistant
	UIDs list is not increasing unbounded.
Change-Id: I475bfee1f0bcd56a750e4fef8aa8a2b93fe090fc