[CARBONDATA-2902][DataMap] Fix showing negative pruning result for ex…

…plain command

#2676 used method ByteBuffer.getShort(int index) to get number of blocklets in block, but it used wrong parameter. The index is index of byte instead of index of short. So it needs to multiply bytes of short type

This closes #2697

core/src/main/java/org/apache/carbondata/core/indexstore/blockletindex/BlockDataMap.java

@@ -551,7 +551,8 @@ protected short getBlockletNumOfEntry(int index) {
       // dummy value
       return 0;
     } else {
-      return ByteBuffer.wrap(getBlockletRowCountForEachBlock()).getShort(index);
+      return ByteBuffer.wrap(getBlockletRowCountForEachBlock()).getShort(
+          index * CarbonCommonConstants.SHORT_SIZE_IN_BYTE);
     }
   }