Remove action runners on user deletion (#27902)

- On user deletion, delete action runners that the user has created.
- Add a database consistency check to remove action runners that have
nonexistent belonging owner.
- Resolves https://codeberg.org/forgejo/forgejo/issues/1720

(cherry picked from commit 009ca7223dab054f7f760b7ccae69e745eebfabb)

Co-authored-by: Gusted <postmaster@gusted.xyz>

services/user/delete.go

@@ -10,6 +10,7 @@ import (
 
 	_ "image/jpeg" // Needed for jpeg support
 
+	actions_model "code.gitea.io/gitea/models/actions"
 	activities_model "code.gitea.io/gitea/models/activities"
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
 	auth_model "code.gitea.io/gitea/models/auth"
@@ -90,6 +91,7 @@ func deleteUser(ctx context.Context, u *user_model.User, purge bool) (err error)
 		&pull_model.AutoMerge{DoerID: u.ID},
 		&pull_model.ReviewState{UserID: u.ID},
 		&user_model.Redirect{RedirectUserID: u.ID},
+		&actions_model.ActionRunner{OwnerID: u.ID},
 	); err != nil {
 		return fmt.Errorf("deleteBeans: %w", err)
 	}