Change DATM_ settings with CLM in the name to coordinate with cime

[ekluzek]

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If CLM is removed from DATM_ settings in cime we'll need to coordinate that change in CDEPS. There are a bunch of instances of these in datm config_component.xml and namelist_definition, as well as in the documentation. There's a print statement in datm buildnml that likely should change as well.

https://github.com/ESMCI/cime/issues/3780