testSoundcloudEmbedFormatter is now broken due to wrong default theme

Problem/Motivation

While testing a patch from #3208259: Migrating from Media Entity to Media in core creates a new source field where one already existed I've discovered
that soundcloud shared music URL in SoundcloudEmbedFormatterTest is broken.

Check the https://soundcloud.com/winguy/billie-jean-remix-ft link.

This track was not found. Maybe it has been removed

Steps to reproduce

Just run test locally with an old url:

php core/scripts/run-tests.sh --verbose --module media_entity_soundcloud --sqlite /tmp/drupal/test.sqlite --url http://localhost

Proposed resolution

Replace music URL with (for example) https://soundcloud.com/grouchnz/michael-jackson-billie-jeangrouch-rmx.
I've tried to find a good alternative URL with lot's of likes and shares to assume that it is stable enought :)

Remaining tasks

- Create patch.

User interface changes

N/A

API changes

N/A

Data model changes

N/A