fix: ensure identities are returned in a consistent order across DB engines (#2465)

Returns identities in a consistent order to work across DB engines.

Previously, we were relying on Postgres' implicit ordering which is
considered an implementation detail and does not carry across to Oriole
DB
(https://github.com/supabase/auth/actions/runs/24069608972/job/70203207256?pr=2464).

Although we don't have an index on created_at, this should be fine since
a user is unlikely to have many indexes and `FindProvidersByUser`
filters by the user_id first.

Related: #2464

Author: fadymak

internal/models/identity.go

@@ -103,7 +103,7 @@ func FindProvidersByUser(tx *storage.Connection, user *User) ([]string, error) {
 	identities := []Identity{}
 	providerExists := map[string]bool{}
 	providers := make([]string, 0)
-	if err := tx.Q().Select("provider").Where("user_id = ?", user.ID).All(&identities); err != nil {
+	if err := tx.Q().Select("provider").Where("user_id = ?", user.ID).Order("created_at asc").All(&identities); err != nil {
 		if errors.Cause(err) == sql.ErrNoRows {
 			return providers, nil
 		}