ci(workflow): add appdir underscore test to subset (#4688)

### Description

Depends on vercel/next.js#48792 - once PR lands,
we should able to run corresponding test cases.

.github/workflows/nextjs-integration-test.yml

@@ -209,7 +209,8 @@ jobs:
         test/development/acceptance-app/unsupported-app-features.test.ts \
         test/development/acceptance-app/ReactRefresh.test.ts \
         test/development/basic/legacy-decorators.test.ts \
-        test/integration/plugin-mdx-rs/test/index.test.js
+        test/integration/plugin-mdx-rs/test/index.test.js \
+        test/e2e/app-dir/underscore-ignore-app-paths/underscore-ignore-app-paths.test.ts
 
     strategy:
       matrix: