General: Remove noreferrer from wp_targeted_link_rel() and other uses.

When `noopener noreferrer` was originally added in #37941 and related tickets, the `noreferrer` bit was specifically included due to Firefox not supporting `noopener` at the time.

Since `noopener` has been supported by all major browsers for a while, it should now be safe to remove the `noreferrer` attribute from core.

Props Mista-Flo, audrasjb, joostdevalk, jonoaldersonwp, peterwilsoncc, elgameel.
Fixes #49558.
Built from https://develop.svn.wordpress.org/trunk@49215


git-svn-id: http://core.svn.wordpress.org/trunk@48977 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/comment.php

@@ -3647,7 +3647,7 @@ function wp_comments_personal_data_exporter( $email_address, $page = 1 ) {
 				case 'comment_link':
 					$value = get_comment_link( $comment->comment_ID );
 					$value = sprintf(
-						'<a href="%s" target="_blank" rel="noreferrer noopener">%s</a>',
+						'<a href="%s" target="_blank" rel="noopener">%s</a>',
 						esc_url( $value ),
 						esc_html( $value )
 					);