Make sure the GSI develop can handle model background fields from current operational system (gfs.v16.3)

[emilyhcliu]

The recent update (PR #743) in GSI develop added the capability of reading in the model fields with Thompson physics, which has two new cloud variables: the number and concentration of cloud ice and rain (ni and nr).
The updated anavinfo is the following:

met_guess::
!var     level    crtm_use    desc              orig_name
  ps        1      -1         surface_pressure     ps
  z         1      -1         geopotential_height  phis
  u       127       2         zonal_wind           u
  v       127       2         meridional_wind      v
  div     127      -1         zonal_wind           div
  vor     127      -1         meridional_wind      vor
  tv      127       2         virtual_temperature  tv
  q       127       2         specific_humidity    sphu
  oz      127       2         ozone                ozone
  ql      127      12         cloud_liquid         ql
  qi      127      12         cloud_ice            qi
  qr      127      12         rain                 qr
  qs      127      12         snow                 qs
  qg      127      12         graupel              qg
  ni      127       1         cloud_ice conc       ni
  nr      127       1         rain conc            nr

However, the updated code can not work with the original anavinfo anymore (see below).

met_guess::
!var     level    crtm_use    desc              orig_name
  ps        1      -1         surface_pressure     ps
  z         1      -1         geopotential_height  phis
  u       127       2         zonal_wind           u
  v       127       2         meridional_wind      v
  div     127      -1         zonal_wind           div
  vor     127      -1         meridional_wind      vor
  tv      127       2         virtual_temperature  tv
  q       127       2         specific_humidity    sphu
  oz      127       2         ozone                ozone
  ql      127      12         cloud_liquid         ql
  qi      127      12         cloud_ice            qi
  qr      127      12         rain                 qr
  qs      127      12         snow                 qs
  qg      127      12         graupel              qg

To make GSI code backward compatible for model fields from gfs.v16.3, the subroutine general_read_gfsatm_allhydro_nc in general_read_gfsatm.f90 needs to be modified.

[emilyhcliu]

Working branch is feature/hydro
The branch was tested on ORION two sets of ICs on 2024021900:

1. background fields from v17 (/work2/noaa/da/eliu/ICs/UFO_eval/data/para/output_ufo_eval_feb2024/)
2. background fields from operational gfs.v16.3 (/work2/noaa/da/eliu/ICs/GDAS_ops/)

The updated code can handle background fields from gfs.v16.3 and v17.
The updated code will not change the results of regression tests.