Document Harbor Registry limitations in Geo and disaster recovery

Problem

Harbor Registry integration does not store any artifacts in GitLab - it only queries data from the source Harbor instance. This means GitLab does not support any disaster recovery functionality for Harbor Registry data.

Proposal

Document Harbor Registry limitations in the following locations:

• Add Harbor Registry to Geo data types limitations
• Add entry to Geo Known issues section
• Update Harbor integration documentation to clarify disaster recovery limitations
• Document limitations in Backup/Restore documentation
• Update Dedicated documentation if applicable
• Update GitLab.com documentation if applicable

Context

The Harbor Registry integration provides a way to view Harbor images in GitLab but does not replicate or backup any Harbor data. Users should be aware that Harbor Registry data is not included in Geo replication, backup/restore operations, or any GitLab disaster recovery processes.