Remove legacy auth usage of $_SESSION (#10491)

* Remove auth use of $_SESSION

Will break plugins that depend on $_SESSION, Weathermap was already fixed.
Port them to use Auth::check()/Auth::user()/Auth:id()

* revert accidental replacement

includes/html/forms/delete-poller.inc.php

@@ -23,9 +23,7 @@
  * @author     Tony Murray <murraytony@gmail.com>
  */
 
-use LibreNMS\Authentication\LegacyAuth;
-
-if (!LegacyAuth::user()->hasGlobalAdmin()) {
+if (!Auth::user()->hasGlobalAdmin()) {
     $status = array('status' =>1, 'message' => 'ERROR: You need to be admin to delete poller entries');
 } else {
     $id = $vars['id'];