Strip password-mask line: it belongs to #1862, not this PR

Inadvertently pulled the password-column mask
(safe_value = "***" if column == PASS else value) into this PR while
restructuring the validation loop for the warn-on-unknown-auth
change. The mask is #1862's core content and shouldn't sneak in
through the site-role decompose PR -- reviewers on either PR would
see mysterious overlap. #1862's full feature (log mask + INFO->DEBUG
downgrade + _redact_password_column helper for invalid_lines
sanitization) stays where it belongs, on jac/csv-import-privacy.

The `column = ColumnType(i)` local rename stays because it's used
by the log line's `{column.name}` format and by the AUTH branch's
comparison; that's plain cleanup and doesn't overlap with #1862.

Author: jacalata

tableauserverclient/models/user_item.py

@@ -582,9 +582,7 @@ def _validate_import_line_or_throw(incoming, logger) -> None:
                             skip_validation = True
                     else:
                         value = value.lower()
-                # Mask the password column so it never reaches log handlers.
-                safe_value = "***" if column == UserItem.CSVImport.ColumnType.PASS else value
-                logger.debug(f"column {column.name}: {safe_value}")
+                logger.debug(f"column {column.name}: {value}")
                 if not skip_validation:
                     UserItem.CSVImport._validate_attribute_value(value, valid, column)