le_audio: state_machine: Fix Data Path not being removed

This fixes bug when Data Path being in CONFIGURING state was not removed.
CONFIGURING state means the Setup ISO Data Path complete event is pending.

Bug: 393101186
Flag: Exempt; regression covered by unit test added
Test: atest bluetooth_le_audio_test
Change-Id: I5d295245aeb8072bd8cc032d33dc79c7803ba10c