leaudio: Improve removing autoconnect from the LeAudio set

If e.g. one of the earbud is in the box and is in autoconnect mode, and
user disconnectes the other device, which clears autoconnect flag on
that device, stack shall also remove from autoconnect the other set
members.

Bug: 263069663
Test: atest BluetoothInstrumentationTests
Test: connect to 2 earbuds, put one into box, disconnect the other
Tag: #feature

Merged-In: Ibec9c9d1c3938c029a672db6135dc277ec5b59c5
Change-Id: Ibec9c9d1c3938c029a672db6135dc277ec5b59c5
(cherry picked from commit afb96f8b)