chore: Restrict MMI test runs

The standard MMI e2e test suite now only runs on long-running branches,
and for MMI-related changes. This should reduce CircleCI credit usage
substantially.

.circleci/config.yml

@@ -176,6 +176,7 @@ workflows:
       - prep-build-test-mmi:
           requires:
             - prep-deps
+            - check-mmi-trigger
       - prep-build-test-mmi-playwright:
           requires:
             - prep-deps
@@ -802,6 +803,7 @@ jobs:
       - run: corepack enable
       - attach_workspace:
           at: .
+      - run: *check-mmi-trigger
       - run:
           name: Build extension for testing
           command: yarn build:test:mmi