Update owners for core/java/android/service/gatekeeper

Include the up-to-date gatekeeper owners from system/gatekeeper, as well
as the locksettings owners since the only file in this directory
(GateKeeperResponse.java) is used only by locksettings related code.

Change-Id: I7c840cb906bc4b56acd007223186811fd3671f5b