oEmbed: Remove the oEmbed provider unit tests.

This reverts [38454] along with its follow-up commits, [38512], [38514], and [38692]. These tests are currently not pass
ing, and maybe they never will. The tests are in a group which does not run by default without a flag, making them quest
ionably useful.

We can re-visit this at a later date.

See #32360


git-svn-id: https://develop.svn.wordpress.org/trunk@38840 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/includes/bootstrap.php

@@ -137,7 +137,6 @@ class WP_PHPUnit_Util_Getopt extends PHPUnit_Util_Getopt {
 			'ajax' => true,
 			'ms-files' => true,
 			'external-http' => true,
-			'external-oembed' => true,
 		);
 
 		foreach ( $options as $option ) {