Set visibility property always to the entry widget

When the password widget has autocomplete activated, the entry is a combobox.

Closes #13166

tryton/tryton/gui/window/view_form/view/form_gtk/char.py

@@ -172,4 +172,8 @@ class Password(Char):
             self.visibility_checkbox, expand=False, fill=True, padding=0)
 
     def toggle_visibility(self, button):
-        self.entry.props.visibility = not self.entry.props.visibility
+        if self.autocomplete:
+            entry = self.entry.get_child()
+        else:
+            entry = self.entry
+        entry.props.visibility = not self.entry.props.visibility