Get single point surface datasets from subset_data rather than mksurfdata

[ekluzek]

Description of changes

Get the single point surface datasets to be created using subset_data rather than mksurfdata.

Specific notes

Contributors other than yourself, if any: @negin513

CTSM Issues Fixed (include github issue #): Fixes #1676 Fixes #1674 Fixes #1809

Are answers expected to change (and if so in what way)? Yes (for single point sites)

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

Testing performed, if any: just running make for single point dataset files in tools/mksurfdata_map