Test coverage for query retries when there is a network partition

The initial version of transparent query retries just adds coverage for retrying a query if an impalad crashes. Now that the Impala has an RPC fault injection framework (IMPALA-8138) based on debug actions, integration tests can introduce network partitions between two impalad processes.

Node blacklisting should cause the Impala Coordinator to blacklist the nodes with the network partitions (IMPALA-9137), and then transparent query retries should cause the query to be successfully retried.