Camera VTS: Fix incorrect return value check

The AIDL interface specificies that ICameraProvider::setCallback should
return Status::ILLEGAL_ARGUMENT if the provided callback is null. The
setCallback test incorrectly checked for the return value to be OK
instead.

This CL fixes the test to check for ILLEGAL_ARGUMENT and removes setting
callback to null from setTorchMode test. In addition it fixes
`setCallback` test to use Bn* variant of ICameraProviderCallback to
ensure that the object makes it through the binder.

Bug: 233221359
Test: atest VtsAidlHalCameraProvider_TargetTest
Change-Id: Ia33226b15efd9628bf8e1b53ec2a3012b08eaaac