Revert "Remove Undocumented Property" (#10544)

* Revert "Remove undocumented property which does not pass mypy checks after an…"

This reverts commit 21a4633.

* add code comment

core/dbt/context/providers.py

@@ -974,7 +974,8 @@ def load_agate_table(self) -> "agate.Table":
             table = agate_helper.from_csv(path, text_columns=column_types, delimiter=delimiter)
         except ValueError as e:
             raise LoadAgateTableValueError(e, node=self.model)
-
+        # this is used by some adapters
+        table.original_abspath = os.path.abspath(path)
         return table
 
     @contextproperty()