atm-regridding-SE_vs_FV

[nanr]

This problem shows up in the AMWG with these settings:

ATMDIAG_test = SE
ATMDIAG_cntl = FV

ATMDIAG_test_regrid" value="True"
ATMDIAG_cntl_regrid" value="False"

Problem: The atm_diagnostics tries to regrid the FV case, even when:
ATMDIAG_cntl_regrid" value="False"