Fix zuul-release-git-prep-upper-constraints
Fix zuul-release-git-prep-upper-constraints

ZUUL_REFNAME is only available in post jobs. To use this macro
everywhere, we need to fallback to ZUUL_REF.

Change-Id: I817d985c00a7ca9c59e02fc22b2a00dd42b72d87

Tesora/tesora-project-config,openstack-infra/project-config,openstack-infra/project-config,Tesora/tesora-project-config