Revert^2 "Use Collections for empty list return"

This reverts commit a9ddf816.

Reason for revert: Relanding the feature after proper testing

Delta with original CL is in audio_util/helpers/Util.java
The toMetadataList should return a modifiable list and not an immutable
collection

Bug: 331250048
Bug: 331494257
Test: atest BluetoothInstrumentationTests
Flag: Exempt, code cleanup
Change-Id: I84b1eab66dc7f4da3ef4e65d4bdaa8f5a0f847f9