Fix Telegraf configuration template

Remove the erroneous curly braces that prevent the Telegraf
configuration template from being rendered.

Change-Id: Ibb8738b258245b4e43d5d877b156ed296fc66e4e
Closes-Bug: 1810505

ansible/roles/telegraf/templates/telegraf.conf.j2

@@ -78,7 +78,7 @@
 {% endif %}
 {% if inventory_hostname in groups['redis'] and enable_redis | bool %}
 [[inputs.redis]]
-  servers = ["{{ tcp://:{{ redis_master_password }}@{{ api_interface_address }}:{{ redis_port }}"]
+  servers = ["tcp://:{{ redis_master_password }}@{{ api_interface_address }}:{{ redis_port }}"]
 {% endif %}
 {% if inventory_hostname in groups['zookeeper'] and enable_zookeeper | bool %}
 [[inputs.zookeeper]]