Widget Factory: remove inline toolbar buttons

Fixes https://gitlab.gnome.org/GNOME/gtk/-/issues/3369

demos/widget-factory/widget-factory.ui

@@ -2035,34 +2035,6 @@ microphone-sensitivity-medium-symbolic</property>
                                         </child>
                                       </object>
                                     </child>
-                                    <child>
-                                      <object class="GtkBox">
-                                        <style>
-                                          <class name="linked"/>
-                                        </style>
-                                        <child>
-                                          <object class="GtkButton" id="decrease_button">
-                                            <property name="icon-name">zoom-out-symbolic</property>
-                                            <property name="tooltip-text">Normal icons</property>
-                                            <signal name="clicked" handler="decrease_icon_size" object="iconview1" swapped="yes"/>
-                                          </object>
-                                        </child>
-                                        <child>
-                                          <object class="GtkButton" id="increase_button">
-                                            <property name="icon-name">zoom-in-symbolic</property>
-                                            <property name="tooltip-text">Large icons</property>
-                                            <signal name="clicked" handler="increase_icon_size" object="iconview1" swapped="yes"/>
-                                          </object>
-                                        </child>
-                                        <child>
-                                          <object class="GtkButton" id="reset_button">
-                                            <property name="icon-name">zoom-original-symbolic</property>
-                                            <property name="tooltip-text">Inherited icon size</property>
-                                            <signal name="clicked" handler="reset_icon_size" object="iconview1" swapped="yes"/>
-                                          </object>
-                                        </child>
-                                      </object>
-                                    </child>
                                   </object>
                                 </child>
                                 <child type="label">