[RFE] Ensure the cluster button is not extended depending on the cluster name

[joaquimrocha]

Current situation

If a cluster has a very long name, it will show up in the cluster button with that name, making the cluster button very wide beyond what's reasonable. E.g.:

Impact

This makes the UX very poor around the cluster chooser.

Ideal future situation

We limit this button's label (and the cluster chooser dialog's buttons) so the cluster name has some ellipses + there's a titletooltip showing the actual cluster's name.