Fixes current user merge request count cache invaldation

What does this MR do and why?

Fixes cache invalidation for when the current user requests a new review

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

How to set up and validate locally

• Enable merge_request_dashboard feature flag
• Assign another user as a reviewer to a merge request
• As that user leave a review or request changes
• As the assignee of the merge request request click the re-request a review button
• The count of merge request should match the count on the http://gdk.test:3000/dashboard/merge_requests page