waterfalls: Clean up obsolete 'waterfall' constants.

This change does three things:

1) Removes unused BRILLO/WEAVE waterfalls.
2) Removes obsolete concept of CIDB supported waterfalls.

The concept of watefalls with CIDB support has been obsolete since
the CIDB migration 00041_alter_build_table_stringify_waterfall.sql.

This change is potentially very significant, because a number of
existing waterfalls were not having their builds inserted into CIDB.

BUG=chromium:768025
TEST=run_tests

Change-Id: I556609392baccb4a9e039d1441997d223e300fba
Reviewed-on: https://chromium-review.googlesource.com/679675
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index a33daa2..7f35e6b 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -752,12 +752,10 @@
 
 def _GetRunEnvironment(options, build_config):
   """Determine whether this is a prod/debug/standalone run."""
-  # TODO(akeshet): This is a temporary workaround to make sure that the cidb
-  # is not used on waterfalls that the db schema does not support (in particular
-  # the chromeos.chrome waterfall).
-  # See crbug.com/406940
+  # Look up the buildbot waterfall.
   wfall = os.environ.get('BUILDBOT_MASTERNAME', '')
-  if not wfall in waterfall.CIDB_KNOWN_WATERFALLS:
+
+  if not wfall:
     return _ENVIRONMENT_STANDALONE
 
   # TODO(akeshet): Clean up this code once we have better defined flags to