Enable `assumeImmutableResults` in incidents list

This commit solves https://gitlab.com/gitlab-org/gitlab/-/issues/338431
It enables `assumeImmutableResults` in the incidents list.

app/assets/javascripts/incidents/list.js

@@ -24,7 +24,7 @@ export default () => {
   } = domEl.dataset;
 
   const apolloProvider = new VueApollo({
-    defaultClient: createDefaultClient(),
+    defaultClient: createDefaultClient({}, { assumeImmutableResults: true }),
   });
 
   return new Vue({