leaudio: Fix possible Assert OnLeAudioDeviceSetStateTimeout

Failing scenario:
1) stream is started and Codec Configure sent to peer device
2) after 1) state_machine.cc starts transition timer
3) device gets disconnected before device response with Codec Configured
 - here all ases are disactivated but transition timeout is still
   enabled
4) transition timeout fires and asserts there is no active device

Bug: 218795097
test: atest --host bluetooth_le_audio_test
Change-Id: Ic6e92a0441fa01b3d5b5b0383b77d0e28fd05924