Avoid redundant addresses.get() in sorted numeric rangeIntoBitSet

[sgup432]

Description

While going through the doc values code where we check the value range for multi valued use-case(and cardinality is not fixed), I see we end up calling 2 decode calls for each doc like below(to calculate the number of values for a doc):

 long startOffset = addresses.get(currentDoc);      
  long endOffset = addresses.get(currentDoc + 1L);   

Seems redundant for consecutive documents. We can avoid one unnecessary addresses.get() call by storing the previous offset. This is what this PR does. Simple change.

[sgup432]

@costin @romseygeek Do you folks mind taking a look at this?

[romseygeek]

Makes sense to me! Do you want to add a CHANGES entry for 10.6?