leaudio: Fix handling OnAudioResume

Blocking this request is not necessary as we always
reply with Pending to the audio framework.
In addition, Bluetooth can either Cancel or Confirm Request imidiatelly
and in Confirm case, there was a race condintion, which leads
to non started session.

Bug: 150670922
Tag: #feature
Sponsor: jpawlowski@
Test: atest --host bluetooth_le_audio_test

Change-Id: I58dcf18e93296fac73485093e33355472d54a0d9