Removed all deprecated _Mysql4_ classes (OpenMage#2730)

* Remove Mysql4 class

* Remove deprecatedNode

* Rename class with Mysql4

* Remove deprecatedNode compatibility

* PHPStan update

* Add migration script

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Co-authored-by: Fabrizio Balliano <[email protected]>

Author: luigifab

app/code/core/Mage/Admin/Model/Mysql4/Acl.php

@@ -28,7 +28,6 @@
             </admin>
             <admin_resource>
                 <class>Mage_Admin_Model_Resource</class>
-                <deprecatedNode>admin_mysql4</deprecatedNode>
                 <entities>
                     <user>
                         <table>admin_user</table>