Execute functional tests in their own builds

Run functional tests outside of the "main" build and run them in parallel on multiple agents (as it's done for the docker tests). Build the pageobjects as part of the "main" build though. This would speed up execution time of func tests. Run this after the "main" build to make sure everything is rebuilt. Also allows to get the artifacts from "main" faster and pushed the test (i.e. quality) validation a bit after.Note: execute in // of "distribution" for tests in "platform-core".

As a side effect, this allows each build to be less long and < than the 4 hours timeout we have ATM.