Remove geo_dependency_proxy_manifest_replication flag

What does this MR do and why?

The MR is intended to remove geo_dependency_proxy_manifest_replication feature flag according to our rollout process. In reality, it removes the alpha notice in API because FF will be used by SSF.

MR acceptance checklist

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

• I have evaluated the MR acceptance checklist for this MR.

Related to #382225 (closed)