Keep detailed job-ended reasons in the history ring

These are all static strings, so the RAM impact is minimal, and it's
quite useful for dumpsys to distinguish between cancel, clean finish,
reschedule, etc.

Bug: 77958513
Test: atest CtsJobSchedulerTestCases
Change-Id: I1e9d918b19b38c458ab24c2e9fb8af856326e1d6