Move tests from kie-plugins-testing Takari to another style

Those tests are run against an old version of maven 

("3.3.9", “3.5.0)

While the current minimum version is now 3.6 see

https://github.com/kiegroup/droolsjbpm-build-bootstrap/blob/master/pom.xml#L405

They can probably migrated to invoker style such as KIE Integration :: Test Coverage

and this should guarantee a faster execution and better logs. 

Check if the invoker style is better and document in a readme.md the invoker style.