PERF: Remove post_upload recovery in daily EnsureS3UploadsExistence job (PR #10173)

This is a very expensive process, and it should only be required in exceptional circumstances. It is possible to run a similar recovery using rake uploads:recover (https://github.com/discourse/discourse/blob/5284d41a8e8cfca1ab5ca21574429f082fb187dd/lib/upload_recovery.rb#L135-L184)

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