ci: exclude the upstream g3 branch from building on CI (#32202)

We don't need to build this branch as it's informative for the purposes of figuring out
the diff between the master and what's synced into google3.

PR Close #32202

.circleci/config.yml

@@ -770,7 +770,10 @@ workflows:
   version: 2
   default_workflow:
     jobs:
-      - setup
+      - setup:
+          filters:
+            branches:
+              ignore: g3
       - lint:
           requires:
             - setup
@@ -900,9 +903,3 @@ workflows:
             branches:
               only:
                 - master
-
-# TODO:
-# - don't build the g3 branch
-# - verify that we are bootstrapping with the right yarn version coming from the docker image
-# - check local chrome version pulled from docker image
-# - remove /tools/ngcontainer