* Reporting phantom and chromium tests should run in parallel.
* Chromium tests should be done in group 9.
* Attempting to use group 2 in ci for chromium tests.
* X-pack CI jobs should have 7 groups.
* Phantom tests should be in group 7.
* [ci][ftr][kbn/test] split up CI jobs
* [ci] run --assert-none-excluded in ci groups, before builds
* [ftr] improve error message when excluded tests found
* [ci] document other places the ciGroups live