Fix for the missing sync bug

Cancel a job before re-scheduling it to avoid
the situation where a job could still be in
JobScheduler's pending queue.

Retry a sync even if it has specified the
do_not_retry extra if the sync failed due
to SyncAlreadyInProgress.

Bug: 27532761
Change-Id: Ia5d2b31fa4e44560a3f170a2bdbf53151bff7a20