bug fix - termination for grazed cohorts

[rgknox]

Description:

This is a critical bug fix, documented here:
NorESMhub/CTSM#218

This solution and changes were written by @JessicaNeedham

Summary: Cohorts were being grazed such that evergreen plants had no leaf or fine-root biomass, this was causing numerical chaos in other aspects of the model. The solution is to terminate these plants.

Collaborators:

Several, see discussion in NorESMhub/CTSM#218

Expectation of Answer Changes:

This can hypothetically change answers in all non-sp configurations, but presumably the differences would be negligable.

Description of generative AI usage (as necessary)

None AFAIK

Checklist

If this is your first time contributing, please read the CONTRIBUTING document.

All checklist items must be checked to enable merging this pull request:

Contributor

• The in-code documentation has been updated with descriptive comments
• The documentation has been assessed to determine if updates are necessary
• Describe use of generative AI (if necessary)

Integrator

• FATES PASS/FAIL regression tests were run
• Evaluation of test results for answer changes was performed and results provided
• FATES-CLM6 Code Freeze: satellite phenology regression tests are b4b

If satellite phenology regressions are not b4b, please hold merge and notify the FATES development team.

Documentation

• Technical Note update:
• User's Guide update:

Test Results:

CTSM (or) E3SM (specify which) test hash-tag:

CTSM (or) E3SM (specify which) baseline hash-tag:

FATES baseline hash-tag:

Test Output:

[rgknox]

re-made branch using a cherry-pick