Declare required jdk as top-level pipeline tool for P- and Y-builds

[HannesWell]

Applies the following changes to P- and Y-builds:

• Declare required jdk and maven as top-level pipeline tools in I-builds #1727
• Revert declaration of maven tool to unbreak sshagent step in I-build #1728

[HannesWell]

Changes have been applied successfully.

In general I have the impression that I-, Y- and P-builds have a lot of configuration in common just like the test job configuration in AutomatedTests and YBuilds and I wonder if it would be desirable to unify this to have one template for the main build and the tests from which all the jobs are generated?