Adjust sticky GC ergonomics.

Added an adjustment factor that causes sticky GC to occur more often.
Currently, we adjust the throughput by 5 / 4 comapred to the non
sticky GC. This improves the MemAllocTest score by 50-100. I believe
this happens since the sticky GC uses less memory bandwidth than
partial/full GC. No benchmark score regression on
EvaluateAndApplyChanges though total GC time is increased by ~0.5s.

Bug: 13818507
Change-Id: Ic721a1bff069ddaf8acc55e776b8bc26e171d46e