Skip Duo review on force-push to a target branch

What does this merge request do and why?

MergeRequests::RefreshService reloads the diff of every merge request that targets a force-pushed branch, and it also scheduled a Duo Code Review for each of them. In a stack, a force-push to the first merge request then started a review on the next merge request too.

This change only schedules the review for merge requests whose source branch got the push.

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

merge request acceptance checklist

Evaluate this merge request against the merge request acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.