SidebarRow: Set ::no-show-all on end_icon_widget

All the other conditionally visible child widgets have this. Without it,
it seems some cases can wrongly reveal it, with a nonsensical home icon.

https://gitlab.gnome.org/GNOME/gtk/issues/1345

gtk/ui/gtksidebarrow.ui

@@ -45,6 +45,7 @@
                     <property name="hexpand">True</property>
                     <property name="halign">end</property>
                     <property name="valign">center</property>
+                    <property name="no-show-all">1</property>
                     <style>
                       <class name="sidebar-icon"/>
                     </style>