Cache compat change values per ProcessRecord for OomAdjuster

Previously looking up the value in the PlatformCompatCache would
require a binary search, since these values won't be changed during
the lifetime of the process, now cache it in Processrecord.

Bug: 197117900
Test: Manual - pprof
Test: atest FrameworksServicesTests:OomAdjusterTests
Test: atest MockingOomAdjusterTests
Test: atest CtsAppTestCases
Change-Id: Iba022bf1ba1634dcd7deeebf71968efd204836da