Fix ORDER BY clause in new regression test of REINDEX CONCURRENTLY

Oversight in bd12080.

Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/20210210065805.GG20012@telsasoft.com
Backpatch-through: 12

src/test/regress/expected/create_index.out

@@ -2645,7 +2645,7 @@ SELECT attrelid::regclass, attnum, attstattarget
     'concur_exprs_index_expr'::regclass,
     'concur_exprs_index_pred'::regclass,
     'concur_exprs_index_pred_2'::regclass)
-  ORDER BY 'concur_exprs_index_expr'::regclass::text, attnum;
+  ORDER BY attrelid::regclass::text, attnum;
          attrelid          | attnum | attstattarget 
 ---------------------------+--------+---------------
  concur_exprs_index_expr   |      1 |           100

src/test/regress/sql/create_index.sql

@@ -1110,7 +1110,7 @@ SELECT attrelid::regclass, attnum, attstattarget
     'concur_exprs_index_expr'::regclass,
     'concur_exprs_index_pred'::regclass,
     'concur_exprs_index_pred_2'::regclass)
-  ORDER BY 'concur_exprs_index_expr'::regclass::text, attnum;
+  ORDER BY attrelid::regclass::text, attnum;
 DROP TABLE concur_exprs_tab;
 
 -- Temporary tables and on-commit actions, where CONCURRENTLY is ignored.