leaudio: Fix for read LeAudio stuff on encryted link

If remote device uses gatt caching, LeAudio mighd start to do searvice
search and read on non encrypted link during pairing.

Bug: 257465691
Test: manual pair multiple times with devices supporting gatt caching
Test: atest BluetoothInstrumentationTests
Tag: #feature
Change-Id: Iec70fa30453871cd95fc494d9e130ae0dbc3c5b1