Reduce memory requirement for tests
Reduce memory requirement for tests

Fork count of 3 often fails on ci.jenkins.io with an out of memory error
in maven.  Use the default and accept slower performance on multi-core
machines.

MarkEWaite/git-plugin,MarkEWaite/git-plugin,martinda/git-plugin,jenkinsci/git-plugin,martinda/git-plugin,jenkinsci/git-plugin,MarkEWaite/git-plugin,martinda/git-plugin,jenkinsci/git-plugin,jenkinsci/git-plugin,MarkEWaite/git-plugin