optional approvals show up wrongly in the activity feed
<!---
Please read this!
Before opening a new issue, make sure to search for keywords in the issues
filtered by the "regression" or "bug" label:
- https://gitlab.com/gitlab-org/gitlab/issues?label_name%5B%5D=regression
- https://gitlab.com/gitlab-org/gitlab/issues?label_name%5B%5D=bug
and verify the issue you're about to submit isn't a duplicate.
--->
### Summary
Text for the optional approvals in activity feed is wrong. It shows up as user opened merge request xyz instead of the user approved merge request xyz.
### Steps to reproduce
- Accept some merge request using optional merge request approvals feature introduced in 13.2
- Check activity feed
### Example Project
https://invent.kde.org/teams/infrastructuretests/repo-insecure/-/merge_requests/12
https://invent.kde.org/teams/infrastructuretests/repo-insecure/activity
### What is the current *bug* behavior?
It shows up as new merge request has been opened.
### What is the expected *correct* behavior?
It should show up as the merge request was approved
### Relevant logs and/or screenshots

issue