Pacemaker HA suport for OVN DB servers

Pacemaker HA suport for OVN DB servers

This patch adds the templates required to enable the OVN DB servers
to be started in master/slave mode in the pacemaker cluster.

For the OVN DBs base profile, ::tripleo::haproxy expects the parameter
'ovn_dbs_manage_lb' set to true in order for it to configure OVN DBs
for load balancing (please see this commit [1]). So this patch sets
'ovn_dbs_manage_lb' to true.

[1] - I9dc366002ef5919339961e5deebbf8aa815c73db

Co-authored-by: Babu Shanmugam (babu.shanmugam@gmail.com)
Depends-on: I94d3960e6c5406e3af309cc8c787ac0a6c9b1756
Change-Id: I60c55abfc523973aa926d8a12ec77f198d885916
Closes-bug: #1670564