yamllint: Make all files in awx pass yamllint

This commit updates all files that weren't passing yamllint for them to
pass.

A new yamllint target has been added. One can run `tox -e yamllint` or
`yamllint -s .` locally to ensure yaml files are still passing.

This check will be enabled in the CI so it can get on every new
contributions, and prevent merging non-compliant code.

Signed-off-by: Yanis Guenane <yguenane@redhat.com>

tools/elastic/kibana/config/kibana.yml

@@ -1,3 +1,4 @@
+---
 # Kibana is served by a back end server. This setting specifies the port to use.
 server.port: 5601
 
@@ -89,4 +90,4 @@ elasticsearch.url: "http://elasticsearch:9200"
 
 # Set the interval in milliseconds to sample system and process performance
 # metrics. Minimum is 100ms. Defaults to 10000.
-# ops.interval: 10000
+# ops.interval: 10000