[SPARK-20333] HashPartitioner should be compatible with num of child RDD's partitions.

## What changes were proposed in this pull request?

Fix test
"don't submit stage until its dependencies map outputs are registered (SPARK-5259)" ,
"run trivial shuffle with out-of-band executor failure and retry",
"reduce tasks should be placed locally with map output"
in DAGSchedulerSuite.

Author: jinxing <jinxing6042@126.com>

Closes #17634 from jinxing64/SPARK-20333.