Wipe LE_AUDIO metadata cache once bonding is complete

Some vendors want to give option to toggle LE Audio. Right now, once
metadata is set, it stays on forever.
After this patch, once bonding attempt is finished, it would be
forgotten.

Test: Bond using FP with LE Audio capable device, then make it not LE
Audio capable and bond again using FP
Flag: EXEMPT, minor tiny little fixt
Bug: 379807136
Bug: 395811008
Change-Id: Ida483a7cb115709da8e5d8338b1de70202536940