Clean up: remove LE audio hardware offload in Bluetooth audio HAL 2.1

LE audio offload plan to fully support on aidl or temporal HAL 2.2. Remove it in HAL 2.1 to make the compatible work easier

Bug: 197296692
Bug: 150670922
Test: HAL 2.1/2.2 work for A2DP software/hardware media, and LE audio
software media/voip call

Change-Id: Icc68bea357d2ee0427826e0c20888399662e9bcb