Fix promtail config when no timeout is configured. (#520)

Author: Gerrit91

partition/roles/promtail/templates/promtail.yaml.j2

@@ -8,7 +8,9 @@ positions:
 clients:
 {% for client in promtail_clients %}
   - url: {{ client.url }}
+{% if client.timeout is defined %}
     timeout: {{ client.timeout }}
+{% endif %}
 {% if client.basic_auth is defined %}
     basic_auth:
       username: {{ client.basic_auth.username }}
@@ -17,4 +19,4 @@ clients:
 {% endfor %}
 
 scrape_configs:
-{{ promtail_scrape_configs | to_yaml(indent=2) }}
+{{ promtail_scrape_configs | to_yaml(indent=2) }}