GPencil: Add missing Pin icon for default eraser

This icon allows to set the default eraser when press Ctrl key and was removed by error in the brush refactor.

release/scripts/startup/bl_ui/properties_paint_common.py

@@ -1194,6 +1194,7 @@ def brush_basic_gpencil_paint_settings(layout, context, brush, *, compact=False)
         row.prop(brush, "size", text="Radius")
         row.prop(gp_settings, "use_pressure", text="", icon='STYLUS_PRESSURE')
         row.prop(gp_settings, "use_occlude_eraser", text="", icon='XRAY')
+        row.prop(gp_settings, "use_default_eraser", text="")
 
         row = layout.row(align=True)
         row.prop(gp_settings, "eraser_mode", expand=True)