Refactor slotScheduleIndexing to make it clearer when each queue runs.

Along the way, fix a couple of odd edge cases:
1. The file queue would sometimes not be started correctly
2. The cleaner would stop when going onto battery, but if we
were already on battery when starting, it would still be started.
Change this so the cleaner runs even when on battery.

Also make some adjustments to the index cleaner so that it works when
resumed: these are only necessary because it is not yet implemented.