Implement finishOperation in shell delegate

Also causes finishProxyOperation to no longer call the finish
implementation on both shell and delegated app

Fixes: 260180018
Test: atest HotwordDetectionServiceBasicTest#testHotwordDetectionService_concurrentCapture
Change-Id: I0bfc6bb6b3c6201158348d5b6777f6a66934f390
2 files changed