Removing an extraneous cigar copy from referenceConfidenceCalculation

[jamesemery]

This was showing up in the profile, as with a few other places this was copying the cigar for each read over each pileup, which is not efficient.
Before:

After:

[codecov-io]

Codecov Report

Merging #5652 into master will increase coverage by 0.005%.
The diff coverage is 100%.

@@              Coverage Diff               @@
##              master    #5652       +/-   ##
==============================================
+ Coverage     87.035%   87.04%   +0.005%     
- Complexity     31726    31728        +2     
==============================================
  Files           1943     1943               
  Lines         146193   146193               
  Branches       16141    16141               
==============================================
+ Hits          127239   127246        +7     
+ Misses         13067    13060        -7     
  Partials        5887     5887

Impacted Files	Coverage Δ	Complexity Δ
...kers/haplotypecaller/ReferenceConfidenceModel.java	92.391% <100%> (ø)	69 <0> (ø)	⬇️
...ithwaterman/SmithWatermanIntelAlignerUnitTest.java	90% <0%> (+30%)	2% <0%> (ø)	⬇️
...utils/smithwaterman/SmithWatermanIntelAligner.java	90% <0%> (+40%)	3% <0%> (+2%)	⬆️

[lbergelson]

looks like a good change