[le audio] Add allow list check when le audio device connected

When le audio device connected, check stored remote model name and compare with
allowlist, then update the flag.

Bug: 301448525
Test: atest bluetooth_le_audio_client_test bluetooth_le_audio_test
Test: manual test with allow list
Change-Id: Ib14b1086446f81f74834ad3557b1056384058be9