ExchangeNode should use getFilteredCardinality for costing.

IMPALA-12018 changed the CPU costing formula from using getCardinality() to getFilteredCardinality() for DataStreamSink, HashJoinNode, JoinNode, and NestedLoopJoinNode. However, it miss to do the same for ExchangeNode, which is also eligible for cardinality reduction by runtime filter.

https://github.com/apache/impala/blob/cdac777c51febc99500b8426c2b3aabc7e9addd7/fe/src/main/java/org/apache/impala/planner/ExchangeNode.java#L236-L237