Fix getHistoricalProcessStartReasons ordering

Ordering is currently done with launch timestamp, however, this is
set to monotonic time since boot which can cause an ordering issue
with persisted records after a reboot.

To fix this, introduce a private created timestamp set to
monotonic time that persists across reboots, thereby ensuring that
records remain ordered by time they were added across reboots and
time changes.

Test: Start device, let run for a bit, trigger a record, wait for
persist, reboot, trigger another record, check and confirm
ordering is correct by making sure they're ordered greatest to
lowest by created time and that timestamp 0 is not ordered.
Test: run new tests

Bug: 360299551

Flag: EXEMPT - bugfix
Change-Id: I45cbae99c6e6848498ba0c668bead099042948ce