Disable keepalived for HA deployments via t-h-t

Disable keepalived for HA deployments via t-h-t

Currently this is disabled via a conditional in the keepalived
profile in puppet-tripleo, but this will be incompatible with
the planned composable upgrades implementation.  Instead we should
disable the service template by mapping to OS::Heat::None, and
ensure the haproxy manifest uses the t-h-t generated hiera value
keepalived_enabled instead of hard-coding a hiera override in the
haproxy template.

Change-Id: I85a8b1cca7268506de22adfb3a8ce7faa4f157ef
Partial-Bug: #1642936
Depends-On: I90faf51881bd05920067c1e1d82baf5d7586af23