fix: Fix thermal conductivity

[dkachuma]

Somewhere along the line the proper resizing of the rock thermal conductivity for the volume weighted model was lost. This was resulting in a seg fault in models using this.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 58.87%. Comparing base (e90dcd2) to head (0663baf).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
...ty/MultiPhaseVolumeWeightedThermalConductivity.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3941   +/-   ##
========================================
  Coverage    58.87%   58.87%           
========================================
  Files         1353     1353           
  Lines       112953   112954    +1     
========================================
+ Hits         66502    66504    +2     
+ Misses       46451    46450    -1     

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[jhuang2601]

Nice catch