fixed a bug where normal p value argument in FilterMutectCalls was static

[davidbenjamin]

@takutosato Silly error on my part. Made the argument parser crash whenever the argument was set to a non-default value.

@Closes #5978.

[codecov]

Codecov Report

Merging #5982 into master will decrease coverage by 0.204%.
The diff coverage is 100%.

@@               Coverage Diff               @@
##              master     #5982       +/-   ##
===============================================
- Coverage     86.929%   86.725%   -0.204%     
+ Complexity     32721     32644       -77     
===============================================
  Files           2013      2013               
  Lines         151306    151354       +48     
  Branches       16610     16622       +12     
===============================================
- Hits          131529    131262      -267     
- Misses         13720     14064      +344     
+ Partials        6057      6028       -29

Impacted Files	Coverage Δ	Complexity Δ
.../mutect/filtering/M2FiltersArgumentCollection.java	94.737% <ø> (+0.142%)	6 <0> (ø)	⬇️
...lkers/mutect/filtering/Mutect2FilteringEngine.java	97.17% <100%> (ø)	45 <0> (ø)	⬇️
...walkers/mutect/filtering/NormalArtifactFilter.java	96% <100%> (+0.348%)	8 <1> (ø)	⬇️
...ils/nio/NioFileCopierWithProgressMeterResults.java	0% <0%> (-94.737%)	0% <0%> (-9%)
...s/spark/ParallelCopyGCSDirectoryIntoHDFSSpark.java	0% <0%> (-74.257%)	0% <0%> (-17%)
...nder/tools/spark/pipelines/PrintVariantsSpark.java	0% <0%> (-66.667%)	0% <0%> (-2%)
...ols/funcotator/FuncotatorDataSourceDownloader.java	0% <0%> (-66.197%)	0% <0%> (-14%)
...nder/utils/nio/NioFileCopierWithProgressMeter.java	17% <0%> (-52.5%)	9% <0%> (-30%)
...oadinstitute/hellbender/utils/gcs/BucketUtils.java	60% <0%> (-18.667%)	32% <0%> (-8%)
...transforms/markduplicates/MarkDuplicatesSpark.java	77.372% <0%> (-13.253%)	50% <0%> (+9%)
... and 9 more