Use new string for South not DES

Currently, we use "SnotDES", which Stephen has pointed out could be interpreted rather rudely. This shows up a few places in the code, so we need to make a careful/comprehensive change.

Grep the repository for 'SnotDES' to locate every occurrence — the issue says it appears in a few places in the LSS catalog code and possibly notebooks. Since the issue does not pin down the replacement, confirm the new string (e.g. 'SouthnotDES') with maintainers before editing. Replace all occurrences consistently, then run the affected notebooks or catalog-generation scripts to confirm nothing depends on the old value.

Written by the indexing model from the issue text.