Only query team tables if repository is under org when getting assignees (#32414)

It's unnecessary to query the team table if the repository is not under
organization when getting assignees.

models/repo/user_repo.go

@@ -110,6 +110,10 @@ func GetRepoAssignees(ctx context.Context, repo *Repository) (_ []*user_model.Us
 		return nil, err
 	}
 
+	uniqueUserIDs := make(container.Set[int64])
+	uniqueUserIDs.AddMultiple(userIDs...)
+
+	if repo.Owner.IsOrganization() {
 		additionalUserIDs := make([]int64, 0, 10)
 		if err = e.Table("team_user").
 			Join("INNER", "team_repo", "`team_repo`.team_id = `team_user`.team_id").
@@ -121,15 +125,13 @@ func GetRepoAssignees(ctx context.Context, repo *Repository) (_ []*user_model.Us
 			Find(&additionalUserIDs); err != nil {
 			return nil, err
 		}
-
-	uniqueUserIDs := make(container.Set[int64])
-	uniqueUserIDs.AddMultiple(userIDs...)
 		uniqueUserIDs.AddMultiple(additionalUserIDs...)
+	}
 
 	// Leave a seat for owner itself to append later, but if owner is an organization
 	// and just waste 1 unit is cheaper than re-allocate memory once.
 	users := make([]*user_model.User, 0, len(uniqueUserIDs)+1)
-	if len(userIDs) > 0 {
+	if len(uniqueUserIDs) > 0 {
 		if err = e.In("id", uniqueUserIDs.Values()).
 			Where(builder.Eq{"`user`.is_active": true}).
 			OrderBy(user_model.GetOrderByName()).