Remove the search_api patch.

Updating a project I got this error:

Could not apply patch! Skipping. The error was: Cannot apply patch https://www.drupal.org/files/issues/2931562-13--undefined_total_in_task_manager_batch_finish.patch

And checking the issue on Drupal.org I noted that the bug has been fixed and the last release contain this fix.

https://www.drupal.org/node/2931562

So, no need to include this patch anymore.