Fix the scheduling of the background dexopt job.

Before this change, when the background dexopt job finishes, it passes
true to jobFinished, which indicates that the job failed and should be
rescheduled.

This CL fixes the bug by always passing false instead. This is correct
because:
- If the job finishes normally, it should not be rescheduled.
- If the job is cancelled by the job scheduler, the job scheduler will
  ignore the jobFinished call. Instead, it will look at the return value
  of onStopJob, which is true.

Bug: 255943027
Test: Presubmit
Change-Id: Ifaabe452aa5fbde9319f84aa8d4e99d7d3350154