Cancel comment reply link broken in AJAX call

[Shelob9]

related #31333 and both of that & this could arguably be a dupe of #31100 but there case appears to be a server config issue, not using cancel_comment_reply_link() or get_comment_link() with AJAX.

cancel_comment_reply_link() has the same issue as get_comment_link() has (#31333) which is that it relies on $_SERVER['REQUEST_URI'] not the actual post permalink for the post's URL.

[rachelbaker]

The fix here isn't as straightforward as #31333 because cancel_comment_reply_link() doesn't allow the comment object or id to be passed in (see #28314 and #30909).

A fix for #28314 would have to land first.