HTML API: Remove empty test file after adding support for missing ele…

…ments.

When support was added for the remaining tags in the IN BODY insertion mode, a test
file indicating that support was necessary for certain parts of the parser was
removed, but it wasn't removed from SVN when sending over the patch from `git`.

This patch removes that empty file so that the WPCS workflows pass.

Discussed in https://core.trac.wordpress.org/ticket/61576

Follow-up to [58779].

See #61576.


git-svn-id: https://develop.svn.wordpress.org/trunk@58780 602fd350-edb4-49c9-b593-d223f7449a82