Fix NPE from unintialized logger in GenotypingEngine

[lbergelson]

• Fixes #Null pointer exception on specific cases (high ploidy values) #8158

[codecov]

Codecov Report

Merging #8159 (9eaceaa) into master (9f77b1f) will increase coverage by 0.000%.
The diff coverage is 100.000%.

Additional details and impacted files

@@             Coverage Diff             @@
##              master     #8159   +/-   ##
===========================================
  Coverage     86.658%   86.658%           
- Complexity     39020     39024    +4     
===========================================
  Files           2337      2337           
  Lines         182958    182959    +1     
  Branches       20080     20079    -1     
===========================================
+ Hits          158547    158548    +1     
+ Misses         17365     17363    -2     
- Partials        7046      7048    +2     

Impacted Files	Coverage Δ
...nder/tools/walkers/genotyper/GenotypingEngine.java	86.250% <100.000%> (+0.086%)	⬆️
...itute/hellbender/tools/LocalAssemblerUnitTest.java	92.448% <0.000%> (ø)

[droazen]

+1