Enable `assumeImmutableResults` in test-case create form

This commit solves https://gitlab.com/gitlab-org/gitlab/-/issues/338572
It enables `assumeImmutableResults` in the test-case create form.

ee/app/assets/javascripts/test_case_create/test_case_create_bundle.js

@@ -15,7 +15,7 @@ export function initTestCaseCreate({ mountPointSelector }) {
   }
 
   const apolloProvider = new VueApollo({
-    defaultClient: createDefaultClient(),
+    defaultClient: createDefaultClient({}, { assumeImmutableResults: true }),
   });
 
   return new Vue({