Failing to pull embed breaks pipeline jobs

Not sure how many of our embeds do this, but at least for Twitter/X, if the job fails to pull a post that's supposed to be embedded, it fails the job.

Example: https://gitlab.com/gitlab-com/content-sites/handbook/-/jobs/6045278752#L103

Should fail gracefully and include the link (or some such) instead of failing all the build jobs.

Options

1. pull the twitter.html shortcode template into the gitlab-docsy theme project and implement error handling there as a stop-gap. See also https://github.com/gohugoio/hugo/blob/master/tpl/tplimpl/embedded/templates/shortcodes/twitter.html
2. Remove twitter embeds and discourage usage in markdown guide.