[QUARANTINE] Verify When pipeline is blocked can still merge MR successfully

What does this MR do?

Quarantines the test Verify When pipeline is blocked can still merge MR successfully (https://gitlab.com/gitlab-org/gitlab/-/blob/master/qa/qa/specs/features/browser_ui/4_verify/pipeline/merge_mr_when_pipline_is_blocked_spec.rb#L71)

This test has been found by Confiner to have failed 4 times, which exceeds the threshold of 3 times.

1. ee:instance-parallel
2. ee:relative_url-parallel
3. ee:update-parallel
4. ee:praefect-parallel

#355297 (closed)

(This MR was automatically generated by Confiner at 2022-04-13 01:33:20 UTC)