Fix content holes in Actions task logs file (#25560)

Fix #25451.

Bugfixes:
- When stopping the zombie or endless tasks, set `LogInStorage` to true
after transferring the file to storage. It was missing, it could write
to a nonexistent file in DBFS because `LogInStorage` was false.
- Always update `ActionTask.Updated` when there's a new state reported
by the runner, even if there's no change. This is to avoid the task
being judged as a zombie task.

Enhancement:
- Support `Stat()` for DBFS file.
- `WriteLogs` refuses to write if it could result in content holes.

---------

Co-authored-by: Giteabot <teabot@gitea.io>

services/actions/clear_tasks.go

@@ -56,12 +56,20 @@ func stopTasks(ctx context.Context, opts actions_model.FindTaskOptions) error {
 			return nil
 		}); err != nil {
 			log.Warn("Cannot stop task %v: %v", task.ID, err)
-			// go on
-		} else if remove, err := actions.TransferLogs(ctx, task.LogFilename); err != nil {
-			log.Warn("Cannot transfer logs of task %v: %v", task.ID, err)
-		} else {
-			remove()
+			continue
 		}
+
+		remove, err := actions.TransferLogs(ctx, task.LogFilename)
+		if err != nil {
+			log.Warn("Cannot transfer logs of task %v: %v", task.ID, err)
+			continue
+		}
+		task.LogInStorage = true
+		if err := actions_model.UpdateTask(ctx, task, "log_in_storage"); err != nil {
+			log.Warn("Cannot update task %v: %v", task.ID, err)
+			continue
+		}
+		remove()
 	}
 
 	CreateCommitStatus(ctx, jobs...)