remove "mean" coupling fields

[DeniseWorthen]

Description

Following ufs-community/ufs-weather-model#1942, the coupled configurations no longer use "mean" coupling fields, for example mean_zonal_moment_flx_atm => GFS_data(nb)%coupling%dusfc_cpl. Only "inst" fields are exported by FV3atm and used by CMEPS, for example inst_zonal_moment_flx => GFS_data(nb)%coupling%dusfci_cpl). The un-used fields should be removed in the interest of code simplification and better user understanding of the coupling.

Solution

Remove any un-needed mean %coupling%X_cpl variable.

Alternatives

Allow the code to continue to maintain un-used variables.