Manager: only log task status change if there is an actual change

Don't log "changes" from, say, `active` -> `active`.

internal/manager/task_state_machine/task_state_machine.go

@@ -80,10 +80,12 @@ func (sm *StateMachine) taskStatusChangeOnly(
 		return fmt.Errorf("saving task to database: %w", err)
 	}
 
+	if oldTaskStatus != newTaskStatus {
 		// logStorage already logs any error, and an error here shouldn't block the
 		// rest of the function.
 		_ = sm.logStorage.WriteTimestamped(logger, job.UUID, task.UUID,
 			fmt.Sprintf("task changed status %s -> %s", oldTaskStatus, newTaskStatus))
+	}
 
 	// Broadcast this change to the SocketIO clients.
 	taskUpdate := webupdates.NewTaskUpdate(task)