1. Make FingerprintEnrollFinish stay on the back stack during "add another" 2. Remove skip button from the enrolling screen, since the user can now back out of the enrollment flow, or back to FingerprintEnrollFinish and press "done" there. Test: Run FingerprintEnrollFinishTest with `am instrument` Bug: 32054268 Change-Id: Icaf017952d6582a14b4d0904b7ee67ad22e5280d