Work on issue #62390590: SecurityException in JobIntentService$...

...JobServiceEngineImpl$WrapperWorkItem.complete

Add more useful information in the security exception message that
is shown -- the reason the last job that was running on the context
was stopped.  This should tell you why when you are calling at that
point your job is no longer running.

Test: bit CtsJobSchedulerTestCases:*

Change-Id: Ia7155248b4b4f032cbf8e8754c5437f658ed192c