Fix up Newton->Ocata rabbitmq ha policy

Fix up Newton->Ocata rabbitmq ha policy

In ocata we changed the ha policy to "ha-exactly" via the following changes:
- tht: Iace6daf27a76cb8ef1050ada0de7ff1f530916c6
- puppet-tripleo: Ib62001c03e1e08f58cf0c6e0ba07a8879a584084

We initially also took care of changing this policy (which is set in the
pacemaker resource agent) for the M/N upgrade path:
I2468a096b5d7042bc801a742a7a85fb1521c1c02

In the end we decided against changing the policy in Newton as well (it
was only for ocata) as it was too close to the release date and we took
the safer path.
This patch does two things:
1) It renames the upgrade function to "newton_ocata" since that is the
only upgrade path we need to take care of
2) It reinstates the actual upgrade function which was mistakenly
removed via an unrelated change in the ceilometer upgrade path:
If9d6987cd0a8fc5d3f9de518ba422d97d5149732

Closes-Bug: #1628998

Change-Id: I3a97505d2ae1ae27f3080ffe74c33fdabffd2420