* The first option in Bluetooth max connected audio devices preference
should be using system default
* Added template based string array to show system default in the list
preference and in preference summary when default is chosen
* Reset max connected audio devices property to empty string when
development setting is disabled or when system default is chosen
* Added instrumentation test to check preference array size and whether
default value is within range of preference array values
* Modified robolectric tests to verify the updated behaviors
Bug: 64767509
Test: Enable and disable multi-device mode in development settings
make -j32 RunSettingsRoboTests
atest SettingsUnitTests:BluetoothMaxConnectedAudioDevicesPreferenceControllerInstrumentationTest
Change-Id: I4915f12df0ac0e6f715e44e0df4a3707dde8d1a4
