If merged, this PR will Remove a blank string that is causing exglobal_cleanup.sh to crash

[andytangborn]

Description

This draft PR is a potential fix to the crashing of the cleanup step for GCAFS. The problem is caused by an empty string and this fix checks for the empty string and changes the script to leave it out.

Resolves #3786

Type of change

• Bug fix

Change characteristics

• Is this a breaking change (a change in existing functionality)? NO
• Does this change require a documentation update? NO
• Does this change require an update to any of the following submodules? NO

How has this been tested?

Cycling many days on gaea.

Checklist

• Any dependent changes have been merged and published
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have documented my code, including function, input, and output descriptions
• My changes generate no new warnings
• New and existing tests pass with my changes
• This change is covered by an existing CI test or a new one has been added
• Any new scripts have been added to the .github/CODEOWNERS file with owners
• I have made corresponding changes to the system documentation if necessary

[CoryMartin-NOAA]

why is eval added here?

[andytangborn]

Leftover from trying to debug. Probably not needed.

[CoryMartin-NOAA]

I think this is the right general idea, but there are changes here that shouldn't be made like extra spaces, prints, and we need to keep all the shellcheck directives. Also, we will need to clean up the PR title/description.