get kibana diagnostics for all kibana nodes

[pmuellr]

In SDH 3539 it was noted that

we also have the option of pushing for the ECE diagnostics tool to collect the output from all Kibana nodes.

The problem noted in the SDH is that we only collect Kibana stats from a single node, but some of the data is node-specific. I think the node-specific data is in the files

• kibana_stats.json
• kibana_status.json
• kibana_task_manager_health.json

It would be good to get the node-specific data for ALL the kibana nodes, not just the one responding to the http requests.