Fix the sign of the heat flux for DISMF

[xylar]

😭😭😭😭😭

Checklist

• Document (in a comment titled Testing in this PR) any testing that was used to verify the changes

[xylar]

@darincomeau and @cbegeman, could you just review this by inspection when you can?

I will post output later this evening.

[cbegeman]

@xylar Yes, I think this is exactly what we want. this is probably obvious, but when you do run the simulations, make sure the conservation AM is on.

[darincomeau]

Looks good to me, thanks @xylar ! Presumably the file in E3SM-Project/E3SM#6256 will then be updated? It'll be easy for me to re-run that case.

[xylar]

Testing

I ran this on the Icos mesh and I'm seeing:

Area of a cell (m^2):             3686400.0
Total flux on plane (kg/s):       30023072.2
Total flux on sphere (kg/s):      30023072.2
Total heat flux on sphere (W):    -10018699206457.0

(I've since changed this to TW for readability.) This seems like the right sign and size of the heat flux, given the mass flux.

[xylar]

I updated the DISMF files for Icos30, SORRM and RRS.