Make RecalculateProjectAuthorizations background migration no-op

What does this MR do?

It removes RecalculateProjectAuthorizations background migration which was added in 12.8. 12.8 is already out of our maintenance policy, and in the meantime, we introduced a periodic recomputation of project authorizations. See the discussion in !41903 (comment 413055449).

This is currently blocking !41903 (closed).

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

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