Preserve import error tables during freeze

- Remove 'import_polygon_%' from UPDATE_TABLES to keep import_polygon_error
and import_polygon_delete tables in frozen databases.

- These tables contain permanent import error tracking data and should not
be deleted during freeze. The ro-access grant system expects them to exist
in all database states.

src/nominatim_db/tools/freeze.py

@@ -18,7 +18,6 @@ UPDATE_TABLES = [
     'address_levels',
     'gb_postcode',
     'import_osmosis_log',
-    'import_polygon_%',
     'location_area%',
     'location_road%',
     'place',