Fix inconsistencies in the ND51/ND51b output fields

Bo Zheng wrote:

   We encountered a potential issue in the satellite diagnostic
   ND51b in v11-01. We find some kind of discontinuity in total
   column AOD (a sum of all aerosol species) along the west-east
   direction. It feels like data are missing/reduced occasionally
   in every other pixels alone the W-E direction. We are running
   v11-01 with full chemistry + UCX driven by MERRA2. The same
   problem remains after switching to MERRA. We checked AOD maps
   in monthly output which looks normal.

This issue was traced to an inconsistency in ND51/ND51b species numbers
in a CASE statement in routine WRITE_DIAG51.  In v11-02 and higher,
the ND51/ND51b tracers were renumbered starting with 500 to account
for the larger number of advected species.  But some of the old tracer
numbers were used to determine which species should have been divided
by array GOOD_CT_CHEM.

Also: now update all ND51/ND51b quantities on every dynamic timestep,
instead having some quantities be updated every timestep and others
be updated only every chemistry timestep.

NOTE: There may be other issues in ND51/ND51b but fixing these will
be a lower priority, as the bpch diagnostic output is slated to be
removed from GEOS-Chem in the near future.

Signed-off-by: Bob Yantosca <yantosca@seas.harvard.edu>