Fix issue #18593636: Turn on "kill important processes that...

...have ballooned" for all devices

Actually, this was supposed to be on for all devices, but it was no
longer being run due to changes in the idle maintenance code in L.
So now we run it again.  And moved the idle maintenance window to 3am.

Change-Id: I8e90723e1431b82896d261cf90f8bf84f43b0bf2