Add an integration test: in case of multi-master, RPC is retried in case of negotiation error with master

In case of multi-master Kudu cluster the client is supposed to retry a failed RPC with other master server.

For example, when the leader master is up but "frozen", if the client times out on negotiating a connection, the RPC fails and should be retried with other available masters.

This is about adding an integration test to cover functionality similar to KUDU-1580, but master-related.