Maven wrapper used by some modules uses older maven then recomended

Summary
When building the repository of kogito-tooling we recommend usage of maven-3.8.1
Allthough the takari wrapper we use in some module (dmn-json-schema-generator, backend-services-extended) use maven 3.6.3

Acceptance criteria
Wrappers use maven we recommend - 3.8.1.
The version should be taken from somewhere so that we do no need to change this every time new mvn release is out