Refresh the code owners asynchronously on push

What does this MR do?

We are trying to improve the performance of the UpdateMergeRequqestsWorker here #218410 (closed) and the sync worker was introduced recently here #326841 (closed). By splitting the UpdateMergeRequqestsWorker out, it will be easier to see where we can target performance improvements.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

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Security

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