Remove demotion flags when a JobWorkItem is enqueued.

Remove the demotion flags from a user-initiated job if the app
successfully enqueues a new JobWorkItem. If an app successfully enqueues
a JobWorkItem to a UI job, then the app is in a state to successfully
schedule a UI job. Presumably, the user has asked for this additional
bit of work, so it makes sense to remove the demotion flags. For now,
we only do this for UI jobs since they have strict scheduling
requirements. It's harder to assume other jobs were scheduled due to
user interaction/request.

This mimics the behavior when a UI job is rescheduled (without adding a
JobWorkItem). Internal flags aren't copied over when a job is
rescheduled.

Bug: 281838527
Test: atest FrameworksMockingServicesTests:JobStatusTest
Change-Id: I591afc7c0ac23fa0bda646fd12053be58ff5d4ee