Remove build dependency on jboss repository-utils maven plugin

[lwrage]

Summary
We currently use a jboss repository-utils p;ugin to add references to external p2 repos to the osate p2 repo. This functionality is now availabe in tycho (see https://github.com/eclipse/tycho/blob/master/RELEASE_NOTES.md#support-for-siterepository-referencelocation-in-eclipse-repository).

Desktop (please complete the following information):

• OSATE Version: 2.10.0
• Operating System: Linux

[lwrage]

closed by f993114