Problem/Motivation
In #2966856: [PP-1] Hide and disable Drupal Migrate Multilingual we keep the Migrate Drupal Multilingual module around for backwards compatibility reasons. Since it is only a shell module to compartmentalize expeirmental multilingual migrations, once it gets stable, it should be removed.
Proposed resolution
Remove in Drupal 9 once we don't need to provide this module anymore. The migrations themselves will all be kept.
Remaining tasks
Do it in Drupal 9.
User interface changes
The module will be gone.
API changes
None.
Data model changes
None.
Release notes snippet
The Migrate Drupal Multilingual module is now removed.