Add change to sa_leaf that was in PPE branch but did not get on master.

Larger than roundoff changes in answers are explained in this post
https://github.com/ESCOMP/CTSM/issues/2777#issuecomment-2371697380
and the diagnostics are here
https://webext.cgd.ucar.edu/I2000/ctsm53n04ctsm52028_f09_saleaf/lnd/ctsm53n04ctsm52028_f09_saleaf_2000_2001_2004-ctsm53n04ctsm52028_f09_2000_2001_2004/setsIndex.html