Explicitly select all columns that appear in order_by

Ref: https://docs.sqlalchemy.org/en/20/changelog/migration_20.html#using-distinct-with-additional-columns-but-only-select-the-entity
Note: this query-building code needs to be converted to SA 2.0; but same
requirement applies.

lib/galaxy/model/__init__.py

@@ -6170,6 +6170,12 @@ def attribute_columns(column_collection, attributes, nesting_level=None):
             q = q.add_entity(entity)
             if entity == DatasetCollectionElement:
                 q = q.filter(entity.id == dce.c.id)
+
+        # Since we will apply DISTINCT, ensure all columns from the ORDER BY clause are explicitly selected
+        for col in order_by_columns:
+            if col not in q.statement._raw_columns:  # do not select a column more than once.
+                q = q.add_column(col)
+
         return q.distinct().order_by(*order_by_columns)
 
     @property