leaudio: Allow to connect profile only when device is bonded

Fixing a race, when profile Connect message reach the native stack just
after device got unbonded.

Bug: 329781005
Test: atest bluetooth_le_audio_client_test
Flag: Exempt, Fixing race which will happen only on the stress tests
Change-Id: I3c018d6fdb74b57eb19b73996068ef35ad35cf80