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/parse-alert-rule.inc.php

@@ -13,9 +13,8 @@
  */
 
 use LibreNMS\Alerting\QueryBuilderParser;
-use LibreNMS\Authentication\LegacyAuth;
 
-if (!LegacyAuth::user()->hasGlobalAdmin()) {
+if (!Auth::user()->hasGlobalAdmin()) {
     header('Content-type: text/plain');
     die('ERROR: You need to be admin');
 }