Add CI to detect stale vis screenshots (#33274)

* Add CI to detect stale vis screenshots

* Remove already installed `tree` command

* Remove workaround for vis silently adding missing screenshots in CI

* Fix stale screenshot detection

* Test that CI doesn't silently create new screenshots

* Discard changes to packages/shared-components/src/room/composer/Banner/Banner.stories.tsx

* Delete stale snapshots

Author: t3chguy

.github/workflows/shared-component-visual-tests-netlify.yaml

@@ -25,9 +25,6 @@ jobs:
             actions: read
             deployments: write
         steps:
-            - name: Install tree
-              run: "sudo apt-get install -y tree"
-
             - name: Download Diffs
               uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
               with:

.github/workflows/shared-component-visual-tests.yaml

@@ -45,11 +45,12 @@ jobs:
               working-directory: packages/shared-components
               run: "pnpm test:storybook --run"
 
-            # Workaround for vis silently adding new baselines if they didn't exist
-            # Can be removed once https://github.com/repobuddy/visual-testing/issues/516 is released
-            - run: |
-                  git add -N .
-                  git diff --exit-code
+            - name: Detect stale screenshots
+              run: |
+                  if diff -rq __baselines__ __results__ | grep "^Only in __baselines__"; then
+                      exit 1
+                  fi
+              working-directory: packages/shared-components/__vis__/linux
 
             - name: Upload received images & diffs
               if: always()