fluentd: pin fluent-plugin-elasticsearch to <5.3.0

5.3.0 requires faraday>2.0, let's pin stable branches requiring
ElasticSearch support.

Closes-Bug: #2019557
Change-Id: I13fe5b46fed3f1ad14eab9fae513617a3d2053c8

Author: mnasiadka

docker/fluentd/Dockerfile.j2

@@ -46,7 +46,7 @@ RUN chmod 755 /usr/local/bin/kolla_extend_start
 {% block fluentd_plugins_install %}
 
 {% set fluentd_plugins = [
-    'fluent-plugin-elasticsearch',
+    'fluent-plugin-elasticsearch:"<5.3.0"',
     'fluent-plugin-grok-parser',
     'fluent-plugin-prometheus',
     'fluent-plugin-rewrite-tag-filter',