Enable EnKF-only for atmosphere

[bhuang95]

What new functionality do you need?

The current global workflow does not support EnKF-only run for the atmosphere. To test existing and future JEDI EnKF development and compare with GSI EnKF, in support of the hybrid 4DEnVar for the atmosphere, we modified the workflow to run EnKF-only in both GSI and JEDI including a minimum set of relevant tasks. These changes will not affect existing applications in the current global-workflow.

Changes were made in associated repos of global-workflow, GDASApp, jcb and jcb-gdas (see detailed description in #4345).

Acceptance Criteria

• With DOENKFONLY_ATM="NO" by default, it should not affect existing applications in the current global workflow. In other words, it should pass all relevant tests following the general guidelines of building the global workflow.
• With DOENKFONLY_ATM="YES" in the config.base during the workflow setup, it should generate related tasks for GSI and JEDI EnKF-only run with additional variable changes in config.base, respectively, and pass all these tasks through rocoto jobs (see Enable EnKF-only for atmosphere #4345).

[bhuang95]

@CoryMartin-NOAA I have created an issue and added corresponding four PRs here. There is still one minor bash script check failed and I have not figured out why yet. But all four PRs should be ready for review. Could you help pinpoint someone in the global workflow team to review those PRs?