Fix ironic's metrics when prometheus exporter enabled

This patch is just fixing ironic's configuration when
ironic's prometheus exporter is turned on. More in
documentation here [1].

[1] https://docs.openstack.org/ironic-prometheus-exporter/latest/configuration.html

Closes-Bug: #2097096
https://review.opendev.org/c/openstack/kolla/+/963258
Signed-off-by: Serhat Rıfat Demircan <[email protected]>
Change-Id: I360f2b7118731554d8fc81cb192809e605b627fc
(cherry picked from commit 55fd5a0)
Signed-off-by: Maksim Malchuk <[email protected]>

Author: keuko

ansible/roles/ironic/templates/ironic.conf.j2

@@ -37,6 +37,11 @@ driver = noop
 location = /var/lib/ironic-metrics
 {% endif %}
 
+{% if enable_ironic_prometheus_exporter | bool %}
+[metrics]
+backend = collector
+{% endif %}
+
 [oslo_messaging_rabbit]
 {% if om_enable_queue_manager | bool %}
 use_queue_manager = true