Refactor remove approvers if not used
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The `ee/app/models/concerns/approval_rule_like.rb` file contains an `approvers` method that does not appear to be called anymore so it should be removed
The following discussion from !134108 should be addressed:
- [ ] @terrichu started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/134108#note_1607626753): (+1 comment)
> **question (non-blocking):** Can this method now be removed? I don't know this area of code well. Perhaps better to be explored in a follow up
issue