Applied fixes from StyleCI (#4106)

Admin/AbstractAdmin.php

@@ -1648,7 +1648,7 @@ which is not the one registered with this admin class ("%s").
 This is deprecated since 3.5 and will no longer be supported in 4.0.
 EOT;
 
-            trigger_error(
+            @trigger_error(
                 sprintf($message, get_class($subject), $this->class),
                 E_USER_DEPRECATED
             ); // NEXT_MAJOR : throw an exception instead

Util/AdminObjectAclData.php

@@ -176,7 +176,7 @@ class AdminObjectAclData
      */
     public function setForm(Form $form)
     {
-        trigger_error('setForm() is deprecated since version 3.0. Use setAclUsersForm() instead.', E_USER_DEPRECATED);
+        @trigger_error('setForm() is deprecated since version 3.0. Use setAclUsersForm() instead.', E_USER_DEPRECATED);
 
         return $this->setAclUsersForm($form);
     }
@@ -190,7 +190,7 @@ class AdminObjectAclData
      */
     public function getForm()
     {
-        trigger_error('getForm() is deprecated since version 3.0. Use getAclUsersForm() instead.', E_USER_DEPRECATED);
+        @trigger_error('getForm() is deprecated since version 3.0. Use getAclUsersForm() instead.', E_USER_DEPRECATED);
 
         return $this->getAclUsersForm();
     }

Util/AdminObjectAclManipulator.php

@@ -72,7 +72,7 @@ class AdminObjectAclManipulator
      */
     public function createForm(AdminObjectAclData $data)
     {
-        trigger_error('createForm() is deprecated since version 3.0. Use createAclUsersForm() instead.', E_USER_DEPRECATED);
+        @trigger_error('createForm() is deprecated since version 3.0. Use createAclUsersForm() instead.', E_USER_DEPRECATED);
 
         return $this->createAclUsersForm($data);
     }
@@ -146,7 +146,7 @@ class AdminObjectAclManipulator
      */
     public function updateAcl(AdminObjectAclData $data)
     {
-        trigger_error('updateAcl() is deprecated since version 3.0. Use updateAclUsers() instead.', E_USER_DEPRECATED);
+        @trigger_error('updateAcl() is deprecated since version 3.0. Use updateAclUsers() instead.', E_USER_DEPRECATED);
 
         $this->updateAclUsers($data);
     }