prometheus: Fix etcd scrape when etcd uses TLS

Use HTTPS to scrape etcd metrics when etcd TLS is enabled.

Change-Id: Iaff10d5314a8dc5b07137d93c269f1ac24cf63de
Closes-Bug: #2036950

ansible/roles/prometheus/templates/prometheus.yml.j2

@@ -203,6 +203,9 @@ scrape_configs:
 
 {% if enable_prometheus_etcd_integration | bool %}
   - job_name: etcd
+{% if etcd_enable_tls | bool %}
+    scheme: https
+{% endif %}
     static_configs:
 {% for host in groups["etcd"] %}
       - targets:

releasenotes/notes/prometheus-etcd-tls-313e7cf454f6763a.yaml

+---
+fixes:
+  - |
+    Fixes an issue where Prometheus scraping of Etcd metrics would fail if Etcd
+    TLS is enabled. `LP#2036950
+    <https://bugs.launchpad.net/kolla-ansible/+bug/2036950>`__