adjust observer yaml files for rrfs-workflow and downstream utilities

[guoqing-noaa]

• Use both short names and long names in the obs space.name. The short names are used as keywords in the downstream applications.
• use short jdiag file names to match rrfs-workflow (downstream applications will also look for short jdiag file names)
• TODO: @OBSFILE@ needs to be replaced with prescribed ioda file names, such as data/obs/ioda_aircar.nc, etc. rrfs-workflow will avoid unnecessary string replacement. But this may affect the ctest, so I will leave this unchanged until a separate new PR.

[delippi]

• I can probably live with the short and long names for obs space, but can you help me understand the exact use case for this? Is it just for the yaml parsing tools and to not have to type the long name fully? Why does one need to use those yaml tools in the first place? What information are you trying to get from those tools that you couldn't get (probably easier) by opening up the file?

• What downstream applications are going to be looking for the short jdiag file names? Couldn't they just use the names as they are now? All of my scripts right now assume the jdiag has the same name convention as the jedi yaml itself (e.g., jdiag_${yamlname}.nc4). I find that much easier. Plus, I feel more verbose names is the way of the JEDI and is just more descriptive for all users.

• What is the NCO standard for the observation file names? I was thinking they needed to have a date string appended to the filename. If that is the case, we would need to keep the @OBSFILE@ placeholder.