Backport CE changes for: Resolves "Reviews: Resolving or unresolving discussions with “Add comment now” does not work"

What does this MR do?

Backports CE changes from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7866

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides