Invalidate the cached async renderer results that depend on the HTTP session, when the session is destroyed

In order to fix XWIKI-21378 we added a new job context store entry (named "request.session") to pass the HTTP session to the jobs that may need it (as is the case with the PDF export job). This means that now we can have async renderer results that depend on the HTTP session, so it would be nice to invalidate those cached entries when the session is destroyed.