make sure that when a refcase is set the drv_restart_pointer filename

[jedwards4b]

is set correctly

Description

• Closes New unintuitive behavior for RUN_TYPE=branch simulations ESCOMP/CMEPS#525

Checklist

• My code follows the style guidlines of this proejct (black formatting)
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have added tests that excerise my feature/fix and existing tests continue to pass
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding additions and changes to the documentation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 31.41%. Comparing base (82493b1) to head (915c5bf).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4905      +/-   ##
==========================================
- Coverage   31.44%   31.41%   -0.04%     
==========================================
  Files         264      264              
  Lines       38703    38741      +38     
  Branches     8390     8402      +12     
==========================================
  Hits        12172    12172              
- Misses      25291    25329      +38     
  Partials     1240     1240              

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[samsrabin]

This works! Tested using the MRE here. After ./preview_namelists the xmlquery successfully gives DRV_RESTART_POINTER: rpointer.cpl.1958-01-01-00000. Thanks, Jim!