Don't unconditionally populate 'iterator' aspect in include_rvar

That causes us to have lots of incorrect 'iterator' aspects in rvar
maps.  Instead, just properly populate the aspects explicitly at the
one relevant call site.

This might help with #6714.

edb/pgsql/compiler/dml.py

@@ -382,6 +382,7 @@ def merge_iterator(
         put_iterator_bond(iterator, select)
         relctx.include_rvar(
             select, iterator_rvar,
+            aspects=('source', 'value', iterator.aspect),
             path_id=iterator.path_id,
             overwrite_path_rvar=True,
             ctx=ctx)

edb/pgsql/compiler/relctx.py

@@ -212,7 +212,7 @@ def include_rvar(
         Compiler context.
     """
     if aspects is None:
-        aspects = ('value', 'iterator')
+        aspects = ('value',)
         if path_id.is_objtype_path():
             if isinstance(rvar, pgast.RangeSubselect):
                 if pathctx.has_path_aspect(