Variable Neighborhood Search for Partitioning Sparse Biological Networks into the Maximum Edge-Weighted < inline-formula> < tex-math notation="LaTeX">$k$ < /tex-math> < alternatives> < mml:math> < mml:mi>k < /mml:mi> < /mml:math> < inline-graphic xlink:href="grbic-ieq1-2898189.gif"/> < /alternatives>