Replaced hidden APIs usage by new SystemApi.

Replaced hidden calls to registerCancelListener and
unregisterCancelListener by new public SystemApis. Also
moved the PendingIntent.addCancelListener to be after
scan setup.

Tag: #feature
Bug: 195146423
Test: Manual
Ignore-AOSP-First: Merge conflict
Change-Id: Ifbfb4af6e946492be892ad2ba80742c044455826