Remove experimental logstash feature.

* We'll most likely be extracting it into a plugin.

config/initializers/100-lograge.rb

@@ -4,8 +4,6 @@ if (Rails.env.production? && SiteSetting.logging_provider == 'lograge') || ENV["
   Rails.application.configure do
     config.lograge.enabled = true
 
-    logstash_uri = ENV["LOGSTASH_URI"]
-
     config.lograge.custom_options = lambda do |event|
       exceptions = %w(controller action format id)
 
@@ -14,23 +12,6 @@ if (Rails.env.production? && SiteSetting.logging_provider == 'lograge') || ENV["
         database: RailsMultisite::ConnectionManagement.current_db,
         time: event.time,
       }
-
-      output[:type] = :rails if logstash_uri
-      output
-    end
-
-    if logstash_uri
-      require 'logstash-logger'
-
-      config.lograge.formatter = Lograge::Formatters::Logstash.new
-
-      config.lograge.logger = LogStashLogger.new(
-        type: :multi_delegator,
-        outputs: [
-          { uri: logstash_uri },
-          { type: :file, path: "#{Rails.root}/log/#{Rails.env}.log", sync: true }
-        ]
-      )
     end
   end
 end