le_audio: Disable Sound Effects for active Broadcast Assistant

While Broadcast Delegator has some source in receive state it may be
receiving broadcast (synced to BIG) or have this source suspended
(ready for/playing unicast stream). Sound Effects causes a unnecessary
delay for suspending Unicast stream, skipping resume for configured
Unicast for Sound Effect improves handover.

Tag: #bug
Bug: 349311566
Bug: 336468573
Test: atest BassClientStateMachineTest
Change-Id: I4811c85feea7636b929524209a1d07f54eb188ae