Gatt: App exception aren't from SystemServer

Calling into mService(IBluetoothGatt) will call the GattService from
Bluetooth app that does not live in the systemServer.
Therefore, exception should be rethrown as runtimeException

Bug: 298264617
Test: atest CtsBluetoothTestCases | Cts does not handled failure in the
      binder nor any of the Test framework we currently have
Change-Id: Ie2ed38e5076242c1001e231f70105890c86ea116