*/*: properly depend on Maven package

devel/maven and devel/maven39 do not provide mvn(1) from LOCALBASE that
one comes from devel/maven-wrapper instead. Therefore, one should depend
on the package rather than a non-existing executable/script.

Approved by: jrm (mentor), otis (mentor), vvd
Differential Revision: https://reviews.freebsd.org/D44229