RunCron.php

<?php
namespace Drupal\sitemanager\Plugin\TaskPlugin;

use Drupal\sitemanager\Plugin\TaskPluginBase;

/**
 * Class RunCron.
 *
 * @package Drupal\sitemanager\Plugin\TaskPlugin
 *
 * @SMTaskPlugin(
 *   id = "run_cron",
 *   taskName = @Translation("Run Cron"),
 *   status = "Waiting",
 * )
 */
class RunCron extends TaskPluginBase {

  public function run($site) {

    $path = $site->getFullSystemPath();

    $response = $this->processService->run('drush cron', $path);

    if ($response['status'] == 'Error') {
      $this->output = [
        '#type' => 'markup',
        '#markup' => $this->t('Error running cron'),
      ];
      $this->pluginDefinition['status'] = 'Error';
    }
    else {
      $this->output = [
        '#type' => 'markup',
        '#markup' => $this->t('Cron run complete'),
      ];
      $this->pluginDefinition['status'] = 'Success';
    }

    return $this->getTaskStatus();

  }
}