Handle JavaBBinderHolder not init w/ mockito

Some mockito users mocking binders like:

    doReturn(...).when(...).asBinder()

Aren't seeing this field initialized when they are making transactions
on this binder object. This causes obtain(IBinder) to fail.

Bug: 252888512
Test: ServiceStateTrackerTest
Change-Id: Ib65948b86cf91f053e26af35629aa3f7d6062c51