[Monitoring/Beats] Telemetry Data from Beats (#18833)

* [Monitoring/Beats] Telemetry Data from Beats

* filter apm-server

* ignore results payload if hitsLength === 0

* process each payload as stats are saved to clusters object

Author: tsullivan

x-pack/plugins/xpack_main/common/constants.js

@@ -23,6 +23,12 @@ export const CONFIG_TELEMETRY_DESC = (
  */
 export const KIBANA_SYSTEM_ID = 'kibana';
 
+/**
+ * The name of the Beats System ID used to publish and look up Beats stats through the Monitoring system.
+ * @type {string}
+ */
+export const BEATS_SYSTEM_ID = 'beats';
+
 /**
  * The name of the Kibana System ID used to look up Logstash stats through the Monitoring system.
  * @type {string}