Enable workhorse upload acceleration for Project Import uploads via UI

What does this MR do?

This is a final MR to enable WH upload acceleration for Imports over UI.
Imports over API are handled in a separate series of MRs.

Previous MRs: !26278 (merged), gitlab-workhorse!470 (merged)

Currently, we support both accelerated and non-accelerated uploads, this will switch to accelerated only.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

I tested locally with

• Object Storage enabled, Direct uploads Enabled
• Object Storage enabled, Direct uploads Disabled
• Object Storage disabled

In all cases the projects imported via API was restored correctly and it was going through and /authorize endpoint first (which is an indicator of being run through the WH).

You could do it as described in !25361 (merged)

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #208674 (closed)