bpo-45436: Fix tkinter tests with Tcl/Tk 8.6.11+ (GH-29077) (GH-29080)

Since v8.6.11, a few configuration options seem to accept an empty value
where they did not previously; particularly the `type` of a `Menu`
widget, and the `compound` of any ttk widget with a label.  Providing an
explicit expected error message to `checkEnumParam` bypasses the check
of an empty value, which no longer raises `TclError`.
(cherry picked from commit 4fe454c6f54b0948af67b53af6c2f35af6377e69)

Co-authored-by: Zachary Ware <zach@python.org>