Fix prometheus-elasticsearch-exporter flags

The flag -es.uri is no longer accepted - it should be --es.uri.
Similarly with -web.listen-address. The following error is seen:

    elasticsearch_exporter: error: unknown short flag '-e', try --help

This change switches to double dashed long options.

Change-Id: I039f4cad970352146462450742056f5990a81b06
Closes-Bug: #1880242

ansible/roles/prometheus/templates/prometheus-elasticsearch-exporter.json.j2

 {
-    "command": "/opt/elasticsearch_exporter/elasticsearch_exporter -es.uri http://{{ api_interface_address | put_address_in_context('url') }}:{{ elasticsearch_port }} -web.listen-address {{ api_interface_address | put_address_in_context('url') }}:{{ prometheus_elasticsearch_exporter_port }}",
+    "command": "/opt/elasticsearch_exporter/elasticsearch_exporter --es.uri http://{{ api_interface_address | put_address_in_context('url') }}:{{ elasticsearch_port }} --web.listen-address {{ api_interface_address | put_address_in_context('url') }}:{{ prometheus_elasticsearch_exporter_port }}",
     "config_files": [],
     "permissions": [
         {