overcloud haproxy lacks client certificate

[Cristian Le]

This affects the connection to horizon backend since the configuration wiht tls-e requires client certificate verification, i.e.:
```
  SSLVerifyClient none
```
However, the haproxy configuration does not seem to be using client certificates:
```
backend horizon_be
  mode http
  cookie SERVERID insert indirect nocache
  option httpchk
  server controller-0.internalapi.openstack.lab 192.168.2.81:443 ca-file /etc/pki/CA/certs/ca2.crt check cookie controller-0.internalapi.openstack.lab fall 5 inter 2000 rise 2 ssl verify required verifyhost controller-0.internalapi.openstack.lab
```
Notice the lack of `crt /path/to/client/certificate` according to [1].

But is client certificate authentication really necessary for this configuration?

[1] https://www.haproxy.com/documentation/hapee/latest/security/authentication/client-certificate-authentication/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/tripleo-heat-templates/+/860910

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Ghanshyam <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/tripleo-heat-templates/+/860910
Reason: TrieplO project is retiring now, for details, please see https://review.opendev.org/c/openstack/governance/+/905145 or reach out to OpenStack TC.