Geo: Remove Geo::Syncable concern

What does this MR do and why?

It removes the Geo::Syncable concern and its inclusion from Geo::JobArtifactRegistry after being migrated to the 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 #408122 (closed)