[Maps] Create new test suite to test showMaps

[thomasneirynck]

As OSS is no longer tested, will need new test-suite to test if xpack.maps.showMapVisualizationTypes: true

The default is false.

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[thomasneirynck]

Discussed offline with @tylersmalley a few weeks ago. Putting feedback here for reference.

Introducing a new test suite adds overhead to CI. Rather than adding more cruft, since the old region/coordinate visualizations will be removed in 8.0, use a single test suite, but configure it differently between 7.x and master.

• 7.x: run test suite with flag on. This is the mainline where the old-visualizations can still be used. test-coverage makes sense.
• master (8.0): turn flag off. The old visualizations will be removed here anyway. There is no need for test-coverage

There is ongoing PR to turn the flag to true by default: https://github.com/elastic/kibana/pull/94968/files. Let this merge first. After, I can create new PR that turns this flag to false, and disable the associated tests.

cc @stratoula

[nreese]

Closing, showMapVisualizationTypes removed in 8.0