Update Vidyard embed code (v4)

Problem/Motivation

Similar to https://www.drupal.org/project/video_embed_vidyard/issues/3055041 we also had a need to utilize Vidyard with the latest embed markup (version 4). The embed markup for the 7.x version is the older iframe markup while version 4 expects a properly formatted img tag.

Proposed resolution

Update `$embed` variable to the be the proper markup.