le_audio: Remove created CIG on ACL Disconnect

When OnLeAudioDeviceSetStateTimeout happens, group will transition
to IDLE, and after that an ACL disconnect will be triggered. We need
to check if CIG is created and if it is, remove it so it can be created
again after reconnect. Otherwise we will get Command Disallowed on CIG Create
when starting stream.

Bug: 270677410
Tag: #feature
Test: atest bluetooth_le_audio_test
Change-Id: I8512b444321c854911350c0ff7388eb5458665ba