Bump gitlab-shell to 14.57.2

What does this MR do and why?

Bumps GITLAB_SHELL_VERSION from 14.57.1 to 14.57.2.

Changes in this release:

• Geo: Fix SSH proxy hang by closing pull request body after negotiation (gitlab-shell!1537 (merged))

This ships the fix for Geo secondary SSH clones failing on slow networks. The SSH proxy kept the proxied HTTP request body open for the whole transfer, so the primary's nginx client_body_timeout killed long pulls. The body is now closed once negotiation completes, with a flush-pkt injected so protocol v2 clients keep working.

References

• Release MR: gitlab-shell!1545 (merged)
• Tag: https://gitlab.com/gitlab-org/gitlab-shell/-/tags/v14.57.2
• Issue: #584782 (closed)

Screenshots or screen recordings

Not applicable, version bump only.

How to set up and validate locally

1. Run gdk update so gitlab-shell is rebuilt at v14.57.2.
2. Confirm the version:

   cat gitlab-shell/VERSION

MR acceptance checklist

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