Make jenkins user own /opt/git for tripleo-ci builds

Altering the jjb configuration to set the current user as owner of /opt/git.
This enables tripleo-ci to leverage the copies of openstack repos that
live in that directory.

Change-Id: Iebe3b5f194682e759266553b0f1e861f2958b048
Merge "Make jenkins user own /opt/git for tripleo-ci builds"