Geo: Rename Files to Blobs

Why are we doing this work

We have been using the terms File and Blob interchangeably but not always in a consistent fashion. This has caused some confusion and ideally we would like to unify on one term.

Per discussions with the team, File is a bit of a loaded term and Blob feels more Geo specific. So we have decided to move towards sticking with one term.

We should update any leftover docs that refer to these items as Files as well as update the UI.

Relevant links

• Data Type Docs: https://docs.gitlab.com/ee/administration/geo/replication/datatypes.html#data-types
• Follow up from conversation: #367087 (comment 2319072713)
• Definition used in the UI: blob_replicator_strategy.rb
• Geo Glossary: https://docs.gitlab.com/ee/administration/geo/glossary.html

Implementation plan

1. Change occurrences of "File" for "Blob" in blob_replicator_strategy.rb;
2. Search for any occurrence of "file" in string form in any geo directory in the codebase to make sure the blob replicator was the only place where we use File when meaning Blob;
3. Consider adding a definition for Blob to the Geo Glossary.