Improve Logging for LFS Object Storage Uploads

While attempting to migrate to LFS object storage, we have run into numerous issues where there are no logs to indicate what had gone wrong. For example, failure to upload because of a permissions error on the GCP creds file needs to be logged somewhere (gitlab-com/migration#252 (comment 64618390)). Another example can be found at gitlab-com/migration#252 (comment 65418083)

The issue illustrating most of these problems is gitlab-com/migration#252 (closed)

cc/ @nolith