[BUGFIX] Avoid unused property in ext:adminpanel

Resolves: #95029
Releases: master
Change-Id: I444aa1b0161c140c40af2dca455246d8336fa4ac
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70813


Tested-by: core-ci <typo3@b13.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/adminpanel/Classes/ViewHelpers/SubModuleRenderViewHelper.php

@@ -33,13 +33,6 @@ class SubModuleRenderViewHelper extends AbstractViewHelper
 {
     use CompileWithRenderStatic;
 
-    /**
-     * First level cache of user names
-     *
-     * @var array
-     */
-    protected static $usernameRuntimeCache = [];
-
     /**
      * Initializes the arguments
      */