Conservative cleanup of frappe.throw/msgprint messages per the message style
guide; meaning, severity, and .format() arguments are unchanged:
- index bare {} placeholders as {0}/{1}/... so translators can reorder
- move f-strings / .format() / concatenation out of _() (they break gettext
extraction and never translate)
- wrap translatable dynamic values (DocType/Select labels) in _()
- fix grammar and colloquialisms
- drop no-op _() wrapping runtime-built strings
Part of #53976.
4efb43d977