Fix teardown for Java integration tests

3ee8a59c made ZK ports non-global which broke teardown in Java
integration tests. This is because the Java integration test helper
does not keep track of the ports assigned to ZK between setup and
teardown calls. This change makes sure that port assignment is called
exactly once during setUp and tearDown.
SplitQuery Java client refactor

Several changes:
Update client to match changes on server side
 - splitsPerShard -> splitCount
 - GetMRSplits -> SplitQuery
Move SplitQuery tests from MapReduceIT to VtGateIT
Lower queryserver-config-schema-reload-time to ensure rdonly tablets
update their schema on new DDLs
Merge pull request #185 from youtube/split-query

Split query