DO NOT MERGE: lmkd: retune rate at which processes are killed

Kill a single process at a time and try to wait up to 100ms for
that process to reclaim memory before triggering another kill.

Test: boots, works
bug: 116877958
Change-Id: I6775d0534b3e3728c04389d3eae1a00e3cbf9f27
(cherry picked from commit afb3a15f)