Auto-merge should not be reset on push
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## Background
With the implementation of `auto-merge` we reset the `auto-merge` status if a push occurs to the branch. However, the [long term vision](https://gitlab.com/gitlab-org/gitlab/-/issues/462286) for `auto-merge` is that we don't want it to be a user action and more something that "just happens".
## Proposal
When a new push is made to the merge request, we should rely on the existing checks/configurations to gate whether or not we merge.
### Additional details
For example, a project can be configured to reset approvals on push. So if we reset the approvals, then that becomes the new gate and once the approvals are given, we'll merge.
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