We create (a currently test only) playbook that upgrades zuul. This job
then runs through project creation and renaming and testinfra testing on
the upgraded gerrit version.
Future improvements should consider loading state on the old gerrit
install before we upgrade that can be asserted as well.
Change-Id: I364037232cf0e6f3fa150f4dbb736ef27d1be3f8
aeddc1bf17