leaudio: Fix cleaning autoconnect flag

Disconnect can be called by Java when connection timeout happen.
We should not treat that in the same way as when device is connected and
user request to disconnect.

Therefor, lets move cleaning autoconnect flag to place, where we know if
device was connected or not.

Bug: 150670922
Bug: 228809876
Sponsor: @jpawlowski
Test: atest --host bluetooth_le_audio_client_test
Change-Id: If0d7fc831bf6da443052d6e05ee1d910818c9a4d
Merged-In: If0d7fc831bf6da443052d6e05ee1d910818c9a4d
(cherry picked from commit ed9e49c7)