Division of MuHash objects are very expensive and multiplication relatively cheap. The whole idea of introducing and tracking numerator and denominators seperately as a representation of the internal state was so that divisions would be rare. So using divison in the Remove method did not make any sense and was just a silly mistake which is corrected here.
This is a partial backport of [[https://github.com/bitcoin/bitcoin/pull/19521 | core#19521]]
https://github.com/bitcoin/bitcoin/pull/19521/commits/9c8a265fd21a87228c18a1661df99fedc1866baf