Rename old StateTracker

- The old StateTracker tracked state through a SimplePredicate defined
with only a "start" atom matcher that matched a state atom. This
StateTracker will be renamed StateConditionTracker to avoid confusion
with the new StateTracker.

Test: bit statsd_test:*
Bug: 136566566
Change-Id: I161aa463e83bd63d0fd52eb8579dab531f566dd5