Zuul trigger no more send GERRIT_* env variable

Recent version of Zuul no more pass GERRIT_* parameters to job. So I
guess we can stop configuring jenkins jobs to use them.

jenkins_jobs/openstack/common/setup.py stills reference GERRIT_REFNAME.
It seems that file got imported from another repository but I have not
found the original repository :(

Change-Id: Ia97319f96a00394b3321a484310975a10f574f13
Merge "Zuul trigger no more send GERRIT_* env variable"