[QUARANTINE] [nightly] Plan Contribution Analytics tests contributions

What does this MR do?

Quarantines the test Plan Contribution Analytics tests contributions (https://gitlab.com/gitlab-org/gitlab/-/blob/master/qa/qa/specs/features/ee/browser_ui/2_plan/contribution_analytics_spec.rb#L45)

This test has been found by Confiner to have failed 6 times, which exceeds the threshold of 3 times.

1. ee:update
2. ce:upgrade
3. ee:instance-image
4. ee:nplus1-instance-image
5. ee:update
6. ee:nplus1-instance-image

#396530 (closed)

(This MR was automatically generated by Confiner at 2023-03-20 01:17:44 UTC)