Direct cache files for HTTPS pages aren't deleted when hitting the apposite button

Hitting the apposite button to delete direct cache files (see screenshot https://snag.gy/p6IegB.jpg), so under `Settings > Directly cached files` will clear only the HTTP version of the directly cached page; the HTTPS version is never deleted. Currently, we have to delete it via FTP.

Start in the WordPress Settings > Directly cached files flow and reproduce the deletion with both HTTP and HTTPS versions of the same page. Trace why the button removes only the HTTP cache entry; done means the button removes both protocol variants, verified by checking that neither direct cache file remains.

Written by the indexing model from the issue text.