Update `$_old_files` to add the deleted MediaElement.js files when it was...

Update `$_old_files` to add the deleted MediaElement.js files when it was upgraded from 2.22.0 to 4.2.3.

Amends [41198].
See #39686.
Fixes #42097.

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git-svn-id: https://core.svn.wordpress.org/trunk@41849 1a063a9b-81f0-0310-95a4-ce76da25c4cd