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/run_attempt.go

@@ -51,10 +51,6 @@ func (attempt *ActionRunAttempt) Duration() time.Duration {
 }
 
 func (attempt *ActionRunAttempt) LoadAttributes(ctx context.Context) (err error) {
-	if attempt == nil {
-		return nil
-	}
-
 	if attempt.Run == nil {
 		run, err := GetRunByRepoAndID(ctx, attempt.RepoID, attempt.RunID)
 		if err != nil {