This patch migrates definition of
neutron-tempest-dvr-ha-multinode-full job to zuul v3 syntax.
Additionally this patch sets l3_ha config option in neutron
to True to make sure that routers created in tests are HA
always.
Change-Id: I3e48c5109dddc2fca6f3b9c289f416ed4a018a41
Related-Bug: #1804844