Fix flaky GraphQL test
https://gitlab.com/gitlab-org/gitlab/-/blob/d5d62d9ff06ba4107d98fdf28912390a21dcd7f7/spec/requests/api/graphql/merge_request/merge_request_spec.rb#L21 frequently times out, causing master-brokenflaky-test incidents.
- gitlab-org/quality/engineering-productivity/master-broken-incidents#5821 (closed)
- gitlab-org/quality/engineering-productivity/master-broken-incidents#5839 (closed)
- gitlab-org/quality/engineering-productivity/master-broken-incidents#5842 (closed)
Clearly something has changed, timing wise.