[autotest] Teach suite scheduler about Tot versions.

In an attempt to get suite scheduler out of the way so the team can
focus on higher priority demands over the next few months, this cl
drops all suites to run tot nightly and older branches weekly by
introducing a couple of new suite scheduler idioms.

TEST=Ran suite scheduler and checked that nightly suites are
     scheduled against localhost.
BUG=chromium:417131,chromium:423847
DEPLOY=suite_scheduler

Change-Id: Ib3f01ac1e6c710ec969cf777d2c872e74a93058a
Reviewed-on: https://chromium-review.googlesource.com/223811
Reviewed-by: Dan Shi <dshi@chromium.org>
Tested-by: Prashanth B <beeps@chromium.org>
Commit-Queue: Prashanth B <beeps@chromium.org>
diff --git a/site_utils/suite_scheduler/driver.py b/site_utils/suite_scheduler/driver.py
index 5869595..fcaec29 100644
--- a/site_utils/suite_scheduler/driver.py
+++ b/site_utils/suite_scheduler/driver.py
@@ -118,6 +118,7 @@
             except board_enumerator.EnumeratorException as e:
                 logging.warning('Failed to enumerate boards: %r', e)
             mv.Update()
+            task.TotMilestoneManager().refresh()
             time.sleep(self._LOOP_INTERVAL_SECONDS)
             self.RereadAndReprocessConfig(config, mv)