Onshore regions are cluster with offshore region shapes, moving the bus centroid over the water

[ktehranchi]

Checklist

• [X] I am using the current master branch
• [X] I am running on an up-to-date pypsa-usa environment. Update via conda env update -f envs/environment.yaml

The Issue

Clustering adjacent onshore regions with offshore regions leads the cluster centroids to be over the water.... This has an impact on the new expected line lengths and the cost associated with upgrading those lines.

Steps To Reproduce

No response

Expected Behavior

Offshore region shapes shouldn't be accounted for in the new cluster centroid shapes.

Error Message

No response

Anything else?

No response