LE Audio Allowlist toggle behavior refactor

The patch contains below behavior changes
1. hide this toggle as the device doesn't enable LE audio profile
2. disable this toggle as bluetooth off, or LE audio feature is disabled
   dynamically
3. disable this toggle if the device doesn't configure to use LE audio
   connection by default
4. switch toggle on to bypass LE Audio allowlist

Bug: 300012501
Test: make RunSettingsRoboTests ROBOTEST_FILTER=BluetoothLeAudioAllowListPreferenceControllerTest
Change-Id: I5ae9c860ba22047fc03ffde7ad3b3f44f9a9a9f0