Re-enable compressed OR boolexpr pushdown (#6948)

To fix the original problem, it is enough to call
eval_const_expressions() to normalize the nested AND boolexprs.

(cherry picked from commit 00fc782)

tsl/src/nodes/decompress_chunk/qual_pushdown.c

@@ -63,8 +63,18 @@ pushdown_quals(PlannerInfo *root, CompressionSettings *settings, RelOptInfo *chu
 		context.can_pushdown = true;
 		context.needs_recheck = false;
 		expr = (Expr *) modify_expression((Node *) ri->clause, &context);
+
 		if (context.can_pushdown)
 		{
+			/*
+			 * We have to call eval_const_expressions after pushing down
+			 * the quals, to normalize the bool expressions. Namely, we might add an
+			 * AND boolexpr on minmax metadata columns, but the normal form is not
+			 * allowed to have nested AND boolexprs. They break some functions like
+			 * generate_bitmap_or_paths().
+			 */
+			expr = (Expr *) eval_const_expressions(root, (Node *) expr);
+
 			if (IsA(expr, BoolExpr) && ((BoolExpr *) expr)->boolop == AND_EXPR)
 			{
 				/* have to separate out and expr into different restrict infos */