ci: use YAML aliases to define branch filters for CircleCI jobs (#33321)

PR Close #33321

.circleci/config.yml

@@ -38,21 +38,26 @@ var_6: &material_unit_tests_cache_key_fallback v4-angular-material-
 # https://circleci.com/blog/deep-diving-into-circleci-workspaces/
 var_7: &workspace_location ~/
 
-# Branch filter that can be specified for jobs that should only run on publish branches
-# (e.g. master or the patch branch)
-var_8: &publish_branches_filter
-  branches:
-    only:
-      - master
-      # e.g. 7.0.x, 7.1.x, etc.
-      - /\d+\.\d+\.x/
-
-# Filter to ignore pull requests on a given job.
-var_9: &ignore_pull_requests
+# Filter to run a job on builds for pull requests only.
+var_8: &only_on_pull_requests
+  filters:
+    branches:
+      only:
+        - /pull\/\d+/
+
+# Filter to skip a job on builds for pull requests.
+var_9: &skip_on_pull_requests
   filters:
     branches:
       ignore:
-        - /pull\/.*/
+        - /pull\/\d+/
+
+# Filter to run a job on builds for the master branch only.
+var_10: &only_on_master
+  filters:
+    branches:
+      only:
+        - master
 
 # Executor Definitions
 # https://circleci.com/docs/2.0/reusing-config/#authoring-reusable-executors
@@ -775,15 +780,13 @@ workflows:
           requires:
             - setup
       - test_saucelabs_bazel:
-          requires:
-            - setup
           # This job is currently a PoC and a subset of `legacy-unit-tests-saucelabs`. Running on
           # master only to avoid wasting resources.
           #
           # TODO: Run this job on all branches (including PRs) as soon as it is not a PoC.
-          filters:
-            branches:
-              only: master
+          <<: *only_on_master
+          requires:
+            - setup
       - test_aio:
           requires:
             - setup
@@ -810,12 +813,10 @@ workflows:
           requires:
             - build-ivy-npm-packages
       - aio_preview:
+          # Only run on PR builds. (There can be no previews for non-PR builds.)
+          <<: *only_on_pull_requests
           requires:
             - setup
-          # Only run on PR builds. (There can be no previews for non-PR builds.)
-          filters:
-            branches:
-              only: /pull\/\d+/
       - test_aio_preview:
           requires:
             - aio_preview
@@ -857,11 +858,11 @@ workflows:
       # This isn't strictly necessary as there is no artifact dependency, but helps economize
       # CI resources by not attempting to build when we know should fail.
       - test_win:
-          <<: *ignore_pull_requests
+          <<: *skip_on_pull_requests
           requires:
             - test
       - test_ivy_aot_win:
-          <<: *ignore_pull_requests
+          <<: *skip_on_pull_requests
           requires:
             - test_ivy_aot
 
@@ -876,9 +877,6 @@ workflows:
             - setup
     triggers:
       - schedule:
+          <<: *only_on_master
           # Runs AIO monitoring jobs at 10:00AM every day.
           cron: "0 10 * * *"
-          filters:
-            branches:
-              only:
-                - master