Finish review fails when "approve" box is checked on already-approved MR

Summary

The "Submit review" button will fail to submit a MR review when you check the "approve MR" box for an MR that you already approved.

Steps to reproduce

1. Create MR in a project that requires at least one approval
2. Add one or more comments to the review
3. Approve the MR
4. Click "Finish review"
5. Check the "Approve merge request" box

Example Project

gitlab-org/govern/demos/sandbox/test-approval-bug!2 (closed)

What is the current bug behavior?

Error appears: "An error occurred while approving, please try again."

What is the expected correct behavior?

Review is submitted. No errors. MR stays approved.

Relevant logs and/or screenshots

Note MR is already approved, which is probably why we get the error:

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes

The request POST https://gitlab.com/gitlab-org/govern/demos/sandbox/test-approval-bug/-/merge_requests/2/drafts/publish fails with:

500 Internal Server Error

{"message":"An error occurred while approving, please try again."}

This is arguably a backend bug. The HTTP status should be 200 with a message of "already approved".