Problem/Motivation
"Convert line breaks into HTML" filter is placing the `drupal-media` tag within a paragraph. It should exclude this tag, as it excludes others, such as `script` and `iframe`.
This is an alternative solution to #3097338: "Convert line breaks into HTML" filter breaks drupalmedia code that adds edit button, where the currently recommended fix is to fix drupalmedia plugin.js to be more flexible about what it encounters inside the widget wrapper.
This was only discovered now because we failed to test media embedding with the "Convert line breaks into HTML" filter enabled. Now more people are using Drupal 8.8 and are trying out the media embed feature, so they are reporting some configurations we didn't test against when building the feature. The "Convert line breaks into HTML" filter isn't really necessary with CKEditor, but the checkbox to enable it doesn't have that fact clearly displayed.
Proposed resolution
Add the `drupal-media` tag to the list of tags to exclude.
Remaining tasks
review, discuss, commit