audio: Add more tests for the "drain early notify" use case

Expand VTS tests by following more possible paths of the stream
state machine.

In the VTS for the core audio HAL, extend the testing framework
to be able to deal with multiple asynchronous callbacks.

Fix a bux in the 'burst' command handling in the default implementation.

Bug: 384431822
Test: atest VtsHalAudioCoreTargetTest
Flag: EXEMPT bugfix
Change-Id: I346c82bef25358e97559b51c38d41b69bebb72e5
2 files changed