ci: Don't run undercoverage when 'pipeline:skip-undercoverage' is set

Signed-off-by: Rémy Coutable <remy@rymai.me>

.gitlab/ci/rules.gitlab-ci.yml

@@ -1367,7 +1367,7 @@
     - <<: *if-not-ee
       when: never
     - <<: *if-merge-request-labels-skip-undercoverage
-      allow_failure: true
+      when: never
     - <<: *if-merge-request-labels-run-all-rspec
     - <<: *if-merge-request
       changes: *backend-patterns