Clean up obsolete simulated satellite product generation from UPP

[WenMeng-NOAA]

The following satellite/instruments might not be in operational now:

• ssmi_f13-20
• imgr_mt2
• imgr_mtlr
• imgr_g11
• imgr_g12
• seviri_m10
• imgr_insat3d
• imgr_g15
• imgr_g13

There are no UPP ID definitions for above simulated satellite products in post_avblflds.xml though UPP IDs are reserved in source code for output. (e.g. ssmi_f13)
Also there are no grib2 names assigned for above simulated satellite products at
https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_table4-2-3-192.shtml
I would think they were added in UPP starting from grib1 output. Can we clean up them from UPP and release UPP ID numbers for new varaibles? @fossell @hertneky @HuiyaChuang-NOAA

[hertneky]

@WenMeng-NOAA You're right, most of those never had Grib2 capabilities. The only ones in that list that did were the GOES 11/12 and it appears they are still in the grib2 table (e.g. SBT112/SBT122...) and post_avlblflds, but as you said not in operation anymore. I think it is safe to remove them all.

[WenMeng-NOAA]

@hertneky Thanks for confirming. I will add this in our UPP to-do list.