Further tuning of PSS collection.

We now keep track of a scaling factor of collection
for each memory state, and allow that to continually
grow as long as the process doesn't come back to it
from a new higher memory state.  This should allow us
to spread out the sample rate for longer-running processes
to be much longer, to reduce the frequency of PSS
collection.

Also moved the decision about when to do a PSS sample of
all processes from some internal timing in the activity
manager to being tied to procstats data commits.  This
makes the interval longer, and ensures after each commit
we have a good initial sample of memory data for all
processes.

Bug: 70859548
Test: atest CtsAppTestCases
Change-Id: Ia3ea2bc9e2d032d51e46e178e2b86b072af9f1ba