Fix custom galaxy cluster connector tag value

[vincenzocaputo]

What does it do?

Fix Issue: #8147

This pull request fixes the connector tag value of custom Galaxy Clusters, using the Cluster name rather then the UUID.

A check on the uniqueness of the connector tag was also added

Questions

• Does it require a DB change?
• Are you using it in production?
• Does it require a change in the API (PyMISP for example)?

[mokaddem]

Hey,
Thanks for your PR but this is the intended behavior. Any custom galaxy clusters have their connector tag with their UUID.
This is mainly for two reasons:

1. Allow duplication of cluster (by forking or if you have different cluster-elements or relationships)
2. To allow the synchronisation of attached tag without leaking the cluster if you're not allowed to see it

Once you have access to the cluster, the connector tag will be replaced by the actual cluster in the UI and API.

Does it make sense?