LFS: Serve pre-signed URLs in `/lfs/objects/batch` (backport to 15.11)

What does this MR do and why?

This is backport of the LFS: Serve pre-signed URLs in `/lfs/objects/batch` (!122221 - merged) to GitLab 15.11.

This is disabled by default, and require enabling feature flag lfs_batch_direct_downloads to make use of this improvements.

The severity2 is assigned due to impact on one of our customers.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the e2e:package-and-test-ee job has either succeeded or been approved by a Software Engineer in Test.

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).