Use AWS SDK v1 for Gitaly backups

What does this merge request do and why?

AWS SDK v2 changed a number of query parameters (https://github.com/google/go-cloud/issues/3476):

• forcePathStyle is now hostname_immutable
• disableSSL is not needed with endpoint

To maintain backwards compatibility, let's just use AWS SDK v1 for now.

How to set up and validate locally

1. Ensure S3 object storage is configured in gdk.yml (should be on by default).
2. Ensure gitaly is up-to-date via gdk update
3. You should see the errors:

2024-09-09_13:53:43.36790 praefect-gitaly-0                  : unclean Gitaly shutdown: resolve backup sink: storage service sink: open bucket: open bucket s3://test1/gitaly_backups?disableSSL=true&s3ForcePathStyle=true&region=gdk&endpoint=http%3A%2F%2F127.0.0.1%3A9000: unknown query parameter "disableSSL"

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.