UI Integration Tests for Region Maps

[kindsun]

We don't currently have a good way to load different region maps with custom attributes for testing. Ideally, we'd like to be able to:

1. Load customized configurations describing different region maps via custom kibana.yml file(s)
2. Test these configurations from the UI

This would fill a gap in our current testing as we develop fixes on our existing branches and also create a repeatable pattern of more robust testing for planned GIS capabilities which we expect to support more layers and more flexible & configurable capabilities moving forward.

[thomasneirynck]

Closing, region maps is deprecated, slated for removal #81703.