Fix Gnocchi tempest.conf generation
Fix Gnocchi tempest.conf generation

[service_available] isn't being generated. This patch fixes it.

Change-Id: I55716e72f7613b47d1832d78fe1658aaa471bd95
Closes-Bug: #1613542

gnocchixyz/gnocchi,leandroreox/gnocchi,sileht/gnocchi,sileht/gnocchi,leandroreox/gnocchi,gnocchixyz/gnocchi