GEOS-JEDI: Super-convergence

This is the issue that I refer to as super convergence:

j3dfgat.jedi_run.log.20231005_03z.txt:jedi_run.csh: JEDI var converged in 40 iterations
j3dfgat.jedi_run.log.20231005_09z.txt:jedi_run.csh: JEDI var converged in 85 iterations
j3dfgat.jedi_run.log.20231005_15z.txt:jedi_run.csh: JEDI var converged in 89 iterations
j3dfgat.jedi_run.log.20231005_21z.txt:jedi_run.csh: JEDI var converged in 89 iterations
j3dfgat.jedi_run.log.20231006_03z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231006_09z.txt:jedi_run.csh: JEDI var converged in 7 iterations
j3dfgat.jedi_run.log.20231006_15z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231006_21z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231007_03z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231007_09z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231007_15z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231007_21z.txt:jedi_run.csh: JEDI var converged in 95 iterations
j3dfgat.jedi_run.log.20231008_03z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231008_09z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231008_15z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231008_21z.txt:jedi_run.csh: JEDI var converged in 101 iterations
j3dfgat.jedi_run.log.20231009_03z.txt:jedi_run.csh: JEDI var converged in 10 iterations
j3dfgat.jedi_run.log.20231009_09z.txt:jedi_run.csh: JEDI var converged in 97 iterations
j3dfgat.jedi_run.log.20231009_15z.txt:jedi_run.csh: JEDI var converged in 101 iterations

As can be seen above there are times when the var stops at very few iterations. These cases, must be understood and used to debug the potential issue triggering these.

The cases above are when JEDI cycles without any input from GSI and the JEDI varBC results are not being cycled; that is, the values are what comes from the IODA converter for each case, as produced offline.

Start by comparing the listed j3dfgat.jedi_run.log.* files, especially the 7- and 10-iteration runs, with the surrounding runs that reached about 101 iterations. Trace the JEDI var convergence behavior for these GSI-free cycles and verify the IODA-converter and varBC conditions described in the issue. Done means the low-iteration cases have a reproducible explanation and the triggering issue is documented or corrected.