Batch-load related data in actions run, job, and task API endpoints (#37032)

Avoid per-item DB queries in ListRuns, ListJobs, and ListActionTasks by
batch-loading trigger users, repositories, and task attributes before
the conversion loop. Remove ReferencesGitRepo from the /actions route
group since no task/run endpoints use it.

Added tests for these endpoints as well.

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>

models/actions/task.go

@@ -125,9 +125,6 @@ func (task *ActionTask) LoadJob(ctx context.Context) error {
 
 // LoadAttributes load Job Steps if not loaded
 func (task *ActionTask) LoadAttributes(ctx context.Context) error {
-	if task == nil {
-		return nil
-	}
 	if err := task.LoadJob(ctx); err != nil {
 		return err
 	}