Workaround for hanging e2e-breaking Babel test (#13623)

* Workaround for hanging e2e-breaking Babel test

* Maybe this

* Update scripts/integration-tests/e2e-babel.sh

* Update scripts/integration-tests/e2e-babel.sh

scripts/integration-tests/e2e-babel.sh

@@ -32,6 +32,15 @@ startLocalRegistry "$PWD"/scripts/integration-tests/verdaccio-config.yml
 node "$PWD"/scripts/integration-tests/utils/bump-babel-dependencies.js
 
 # Update deps, build and test
-make -j test-ci
+if [ "$BABEL_8_BREAKING" = true ] ; then
+  # Jest hangs forever in the Babel 8 e2e test when using multiple workers,
+  # but we don't know yet why. Until we figure it out (see
+  # https://github.com/babel/babel/pull/13618) we can use --runInBand.
+  make -j build-standalone-ci
+  BABEL_ENV=test yarn jest --ci --runInBand
+  make -j test-clean
+else
+  make -j test-ci
+fi
 
 cleanup