Use the id, not plugin_args as plugin info in pipeline reporter for outputs.

The plugin args are not really necessary for reporting. Now that we have unique IDs
that's a better way to figure which output is which without potentially sharing
sensitive data.

This fixes hanging tests in the previous commit

Fixes #5827

logstash-core/lib/logstash/pipeline_reporter.rb

@@ -101,7 +101,7 @@ module LogStash; class PipelineReporter
     pipeline.outputs.map do |output_delegator|
       {
         :type => output_delegator.config_name,
-        :plugin_args => output_delegator.plugin_args,
+        :id => output_delegator.id,
         :concurrency => output_delegator.concurrency,        
       }
     end