Remove unused paramater to finish

the finishWCTCallback forces a sync transaction on finish
and this conflicts with normal transition stuff, so we actually
never use it. This CL removes it since it is deadcode.

Bug: 293889797
Test: N/A, code is dead already.
Change-Id: I27da152c8c9ec7be1ac22a236ceface4e5d497b9
Merged-In: I27da152c8c9ec7be1ac22a236ceface4e5d497b9