make xgrid default, handle main task for multidriver cases in esm_tim…

[jedwards4b]

…e_clockinit

Description of changes

Make xgrid default, fix an issue with maintask in multidriver cases.

Specific notes

Contributors other than yourself, if any:

CMEPS Issues Fixed (include github issue #):

Are changes expected to change answers? (specify if bfb, different at roundoff, more substantial)

Any User Interface Changes (namelist or namelist defaults changes)?

Testing performed

Testing performed if application target is CESM:

• (recommended) CIME_DRIVER=nuopc scripts_regression_tests.py
  • machines:
  • details (e.g. failed tests):
• (recommended) CESM testlist_drv.xml
  • machines and compilers:
  • details (e.g. failed tests):
• (optional) CESM prealpha test
  • machines and compilers
  • details (e.g. failed tests):
• (other) please described in detail
  • machines and compilers
  • details (e.g. failed tests):

Testing performed if application target is UFS-coupled:

• (recommended) UFS-coupled testing
  • description:
  • details (e.g. failed tests):

Testing performed if application target is UFS-HAFS:

• (recommended) UFS-HAFS testing
  • description:
  • details (e.g. failed tests):

Hashes used for testing:

• CESM:
  • repository to check out: https://github.com/ESCOMP/CESM.git
  • branch/hash:
• UFS-coupled, then umbrella repostiory to check out and associated hash:
  • repository to check out:
  • branch/hash:
• UFS-HAFS, then umbrella repostiory to check out and associated hash:
  • repository to check out:
  • branch/hash: