Deactivate output for variable nav_lat and nav_lon for the case grid=regular_xy. For this grid, the default names for the longtiude and latitude dimensions are nav_lon and nav_lat and therfor it is not possible to output variables with the same name.
nav_lat and nav_lon have been added previsoulsy as output in ORCHIDEE to write them in the forcing_by_ORCHIDEE.nc file to be used to force ORCHIDEE in offline mode. But for the regular_xy grid, it is not needed to add nav_lat and nav_lon as they are output automatically by XIOS.
This change makes it possible to output forcing_by_ORCHIDEE.nc also for the case regular_xy grid and corrects the default settings since forcing_by_ORCHIDEE.nc file was activated by default in [8537].
