NCK test isn't actually testing multi-instance - should be MCC

[billsacks]

Due to an issue in CIME, it appears that the NCK test in the aux_glc test suite isn't actually testing multi-instance. It may need a _C2 modifier and/or some fix may be needed in CIME.

See ESMCI/cime#4933 (comment)

[billsacks]

The issue appears to be that NCK is no longer a valid test with NUOPC. This should be changed to MCC.