topology: Delete the need to query CIDB for a constant dictionary

cbuildbot/topology.py queries CIDB for a dictionary which
can live in lib/constants.py without any loss of functionality.

BUG=chromium:904573
TEST=tryjob

Change-Id: I2082e3294b8ad99b4a829dcec8aba43cbfe42e0a
Reviewed-on: https://chromium-review.googlesource.com/1457281
Commit-Ready: Dhanya Ganesh <dhanyaganesh@chromium.org>
Tested-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
Reviewed-by: Jason Clinton <jclinton@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index b3970ae..06e5041 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -812,9 +812,7 @@
     cidb.CIDBConnectionFactory.SetupNoCidb()
     context = ts_mon_config.TrivialContextManager()
 
-  db = cidb.CIDBConnectionFactory.GetCIDBConnectionForBuilder()
-  topology.FetchTopologyFromCIDB(db)
-
+  topology.FetchTopology()
   return context