L2SS-1052: clean logstash config file

docker-compose/logstash/loki.conf

 input {
   beats {
     port => 5044
-    # ssl => true
-    # ssl_certificate => "/etc/pki/tls/certs/logstash-beats.crt"
-    # ssl_key => "/etc/pki/tls/private/logstash-beats.key"
+    # TODO (L2SS-748) add SSL encryption
   }
-}
-
-input {
   syslog {
     port => 1514
   }
-}
-
-input {
   tcp {
     port => 5959
     codec => json
@@ -34,14 +26,6 @@ filter {
   }
 }
 
-# filter {
-#   if [type] == "nginx-access" {
-#     grok {
-#       match => { "message" => "%{NGINXACCESS}" }
-#     }
-#   }
-# }
-
 filter {
   if [program] == "grafana" {
     kv { }
@@ -140,11 +124,6 @@ filter {
 }
 
 output {
-  # elasticsearch {
-  #   hosts => ["localhost"]
-  #   manage_template => false
-  #   index => "logstash-%{+YYYY.MM.dd}"
-  # }
   loki {
     url => "http://loki:3100/loki/api/v1/push"
   }