Camera VTS: Improve test for torch callback

Test below sequence:
- ICameraProvider::setCallback
- setTorchMode(on)
- verify torch mode on callback is received
- ICameraProvider::setCallback
- verify torch mode on callback is received again

This makes sure if torch is on, a new callback registration will trigger
a flash-on callback.

Test: atest VtsAidlHalCameraProvider_TargetTest
Bug: 247038031
Change-Id: I6cea64fcd08fd68fda78b3c0efb7763b7de6edbc