[MINOR] Fix minor mistake in MNC sparsity estimation for row bind operations

[ywcb00]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 39.34%. Comparing base (3de7cbe) to head (b306716).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...che/sysds/hops/estim/EstimatorMatrixHistogram.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##               main    #2469       +/-   ##
=============================================
- Coverage     71.36%   39.34%   -32.03%     
+ Complexity    48688    27151    -21537     
=============================================
  Files          1570     1570               
  Lines        188757   188757               
  Branches      37039    37039               
=============================================
- Hits         134711    74270    -60441     
- Misses        43594   106672    +63078     
+ Partials      10452     7815     -2637     

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