qt: remove unnecessary layout wrapping simple prefs widget

Makes no difference at all to have this.

modules/gui/qt/dialogs/preferences/sprefs_interface.ui

@@ -590,15 +590,11 @@
        </widget>
       </item>
       <item row="1" column="0">
-       <layout class="QHBoxLayout" name="horizontalLayout_3">
-        <item>
-         <widget class="QCheckBox" name="saveRecentlyPlayed">
-          <property name="text">
-           <string>Save recently played items</string>
-          </property>
-         </widget>
-        </item>
-       </layout>
+       <widget class="QCheckBox" name="saveRecentlyPlayed">
+        <property name="text">
+         <string>Save recently played items</string>
+        </property>
+       </widget>
       </item>
       <item row="0" column="2">
        <widget class="QSpinBox" name="updatesDays">