le_audio: ignore connect events in connecting state

After bonding the enabled profiles are connected automatically:

BluetoothAdapterService: connectEnabledProfiles: Connecting LeAudio
and this may happen multiple times. Additionally during testing
LeAudioService::connect() may be invoked causing 2 redundant connect
calls that happen in Connecting state of the LeAudio state machine.
The events are then deferred, and on any failure and the state change to
Disconnected they are being invoked again in Disconnected state.

Bug: 381200144
Bug: 384460395
Flag: com.android.bluetooth.flags.leaudio_sm_ignore_connect_events_in_connecting_state
Test: atest LeAudioStateMachine
Change-Id: I97231165e097d701c4f1b26f307d41713967b96c