scripts: add script to measure percentage of commits with failed status
scripts: add script to measure percentage of commits with failed status

This is to start measuring the test flakiness and see the numbers improving once we improve and deflake flaky tests

Fixes #13167

mqliang/etcd,ajityagaty/etcd,rnaveiras/etcd,rnaveiras/etcd,mqliang/etcd,mkumatag/etcd,mkumatag/etcd,etcd-io/etcd,rnaveiras/etcd,ajityagaty/etcd,ajityagaty/etcd,mqliang/etcd,etcd-io/etcd,mkumatag/etcd,etcd-io/etcd