Add post_itag_gcafs file for the GCAFS model

[zhanglikate]

Commit Queue Requirements:

• This PR addresses a relevant WM issue (if not, create an issue).
• All subcomponent pull requests (if any) have been reviewed by their code managers.
• Run the full Intel+GNU RT suite (compared to current baselines), preferably on Ursa (Derecho or Hercules are acceptable alternatives). Exceptions: documentation-only PRs, CI-only PRs, etc.
  • Commit log file w/full results from RT suite run (if applicable).
  • Verify that test_changes.list indicates which tests, if any, are changed by this PR. Commit test_changes.list, even if it is empty.
• Fill out all sections of this template.

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Description:

Commit Message:

* UFSWM - 

Priority:

• High: Get grib2 output for GCAFS model

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Changes

Regression Test Changes (Please commit test_changes.list):

• PR Adds New Tests/Baselines.
• PR Updates/Changes Baselines.
• No Baseline Changes.

Input data Changes:

• None.

Library Changes/Upgrades:

• No Updates

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Testing Log:

• RDHPCS
  • Hera
  • Orion
  • Hercules
  • GaeaC6
  • Derecho
  • Ursa
• WCOSS2
  • Dogwood/Cactus
  • Acorn
• CI
• opnReqTest (complete task if unnecessary)

[bbakernoaa]

Should this be gcafs?

[WenMeng-NOAA]

The modelname 'GFS' is used internally in UPP to specify global model processing schemes. It applies to GFS, GEFS, and GCAFS processing.

[gspetro-NOAA]

@zhanglikate Could you fill out the Commit Message portion of the template, push your log file showing that you ran the full RT suite, and push your test_changes.list file?