[SPARK-19956][CORE] Optimize a location order of blocks with topology information

## What changes were proposed in this pull request?

When call the method getLocations of BlockManager, we only compare the data block host. Random selection for non-local data blocks, this may cause the selected data block to be in a different rack. So in this patch to increase the sort of the rack.

## How was this patch tested?

New test case.

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: Xianyang Liu <xianyang.liu@intel.com>

Closes #17300 from ConeyLiu/blockmanager.