leaudio: Fix stopping group when in transition to ENABLE

If remote device rejects metadata, Android will stop the stream.
In such case, make sure that CIG is destroyed even there is no yet
any CIS created.

Bug: 300812893
Test: atest bluetooth_le_audio_test
Tag: #feature
Change-Id: I729ac0e30abfcdcc6a61596cbf2e48ce91c9e561