Change format of data for TPS/Finality metrics in testnet automation (#1446)

* Change format of data for TPS/Finality metrics in testnet automation

* Revert number of nodes for testnet automation

* Split python command to its own script

* Fix python command line arguments

ci/testnet-automation-json-parser.py

@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+import sys, json
+
+data=json.load(sys.stdin)
+print[\
+   ([result['series'][0]['columns'][1].encode(), result['series'][0]['values'][0][1]]) \
+   for result in data['results']]