fix test with duplicate foreign key names

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>

Author: shlomi-noach

go/vt/schemadiff/schema_test.go

@@ -287,11 +287,11 @@ func TestTableForeignKeyOrdering(t *testing.T) {
 		"create table t11 (id int primary key, i int, key ix (i), constraint f12 foreign key (i) references t12(id) on delete restrict, constraint f20 foreign key (i) references t20(id) on delete restrict)",
 		"create table t15(id int, primary key(id))",
 		"create view v09 as select * from v13, t17",
-		"create table t20 (id int primary key, i int, key ix (i), constraint f15 foreign key (i) references t15(id) on delete restrict)",
+		"create table t20 (id int primary key, i int, key ix (i), constraint f2015 foreign key (i) references t15(id) on delete restrict)",
 		"create view v13 as select * from t20",
-		"create table t12 (id int primary key, i int, key ix (i), constraint f15 foreign key (i) references t15(id) on delete restrict)",
-		"create table t17 (id int primary key, i int, key ix (i), constraint f11 foreign key (i) references t11(id) on delete restrict, constraint f15 foreign key (i) references t15(id) on delete restrict)",
-		"create table t16 (id int primary key, i int, key ix (i), constraint f11 foreign key (i) references t11(id) on delete restrict, constraint f15 foreign key (i) references t15(id) on delete restrict)",
+		"create table t12 (id int primary key, i int, key ix (i), constraint f1215 foreign key (i) references t15(id) on delete restrict)",
+		"create table t17 (id int primary key, i int, key ix (i), constraint f1711 foreign key (i) references t11(id) on delete restrict, constraint f1715 foreign key (i) references t15(id) on delete restrict)",
+		"create table t16 (id int primary key, i int, key ix (i), constraint f1611 foreign key (i) references t11(id) on delete restrict, constraint f1615 foreign key (i) references t15(id) on delete restrict)",
 		"create table t14 (id int primary key, i int, key ix (i), constraint f14 foreign key (i) references t14(id) on delete restrict)",
 	}
 	expectSortedTableNames := []string{