Quarantine e2e test

qa/qa/specs/features/browser_ui/3_create/merge_request/merge_merge_request_from_fork_spec.rb

@@ -2,7 +2,11 @@
 
 module QA
   RSpec.describe 'Create' do
-    describe 'Merge request creation from fork' do
+    describe 'Merge request creation from fork', quarantine: {
+      only: { subdomain: %i[canary production] },
+      issue: "https://gitlab.com/gitlab-org/gitlab/-/issues/343801",
+      type: :investigation
+    } do
       let(:merge_request) do
         Resource::MergeRequestFromFork.fabricate_via_browser_ui! do |merge_request|
           merge_request.fork_branch = 'feature-branch'