Speed up GSI run in CI tests

[CoryMartin-NOAA]

What new functionality do you need?

In the workflow CI cycling tests, GSI runs with the 'default' number of iterations. These tests are not scientific, so there is no need to run this many variational iterations. We can reduce this in 'testing' mode to speed up analysis jobs.

What are the requirements for the new functionality?

Add in a flag that indicates the CI test is running so make the configuration 'faster/simpler'.

Acceptance Criteria

• cycled tests pass
• some sort of reduction in analysis job walltime

Suggest a solution (optional)

No response