restart fixes for two-stream

[rgknox]

Description:

This set of changes, as well as changes to the host, enable restart tests to pass when two-stream radiation is active. Also, subtle updates were made to zenith angle handling, specifically zenith angle is passed at the site level and there is no need to pass in a zenith active flag. Some minor code clean up is also included.

Synchronize with CTSM #2949

Collaborators:

@ckoven

Expectation of Answer Changes:

This may change answers slightly, but should not have any meaningful science changes.

Checklist

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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

Integrator

• FATES PASS/FAIL regression tests were run
• Evaluation of test results for answer changes was performed and results provided

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]

Note: this branch merged in luh2_nocomp_merge-bcindex from #1226

[glemieux]

This should address ESCOMP/CTSM#2325, correct?

[rgknox]

yes, I'll like the fix on the ctsm side of the PR