Keep warming services out of cached adj

Add a pre-configured list that will help to prevent those services
which will keep critical code path of the host processes warm
from falling into cached adj; in case of multi-user, such service
running in the background user won't get this capability, unless it's
singleton.

The list will be empty by default and subjected to be overlaid
by device configurations.

Bug: 158685897
Test: atest MockingOomAdjusterTests
Test: Manual - Add test service into the pre-configured list
      start it and verify it won't get into cached state
Change-Id: I062f5ec3947ad3acebcc2ffe79e420beb23443a2