leaudio: Fix invalid state report from group state machine

Before sending STREAMING status to client.cc, make sure that Stop group
has not been initiated. Otherwise client.cc would get unexpected message
from state machine and assert.

This patch also adds test which reproduce the issue, and also change the
way state machine handles multiple devices when release ASEs.
From now on, Release command will be send simultaneously, to avoid
getting state machine in wrong state, when  one of the device disconnects
during the Release operation.

Bug: 271957165
Tag: #feature
Test: atest BluetoothInstrumentationTests
Test: atest bluetooth_le_audio_test
Change-Id: If4a917f7347b84a19b115b199e624c40eac7ad35