Remove redundant indexes (#17710)

store/sqlstore/user_store.go

@@ -82,7 +82,6 @@ func newSqlUserStore(sqlStore *SqlStore, metrics einterfaces.MetricsInterface) s
 }
 
 func (us SqlUserStore) createIndexesIfNotExists() {
-	us.CreateIndexIfNotExists("idx_users_email", "Users", "Email")
 	us.CreateIndexIfNotExists("idx_users_update_at", "Users", "UpdateAt")
 	us.CreateIndexIfNotExists("idx_users_create_at", "Users", "CreateAt")
 	us.CreateIndexIfNotExists("idx_users_delete_at", "Users", "DeleteAt")