Quarantine QA test content_editor_spec and project_templates_spec

What does this MR do?

MR quarantines content_editor_spec and project_templates_spec as they affect multiple pipelines widely.

E2E Test Failure issue(s)

• #350220 (closed)
• #350279 (closed)
• #350280

Check-list

• General code guidelines check-list
  • Code review guidelines
  • Style guides
• Quarantine test check-list
  • Follow the Quarantining Tests guide.
  • Confirm the test has a quarantine: tag with the specified quarantine type.
  • Note if the test should be quarantined for a specific environment.
  • (Optionally) In case of an emergency (e.g. blocked deployments), consider adding labels to pick into auto-deploy (Pick into auto-deploy priority1 severity1).
• Dequarantine test check-list
  • Follow the Dequarantining Tests guide.
  • Confirm the test consistently passes on the target GitLab environment(s).
    • (Optionally) Trigger a manual GitLab-QA pipeline against a specific GitLab environment using the RELEASE variable from the package-and-qa job of the current merge request.
• To ensure a faster turnaround, ask in the #quality Slack channel for someone to review and merge the merge request, rather than assigning it directly.