Fix up previous edebug breakpoint overlay change
* lisp/emacs-lisp/edebug.el (edebug--overlay-breakpoints): Only make the overlays in edebug mode, so that we remove them when we exit.
* lisp/emacs-lisp/edebug.el (edebug--overlay-breakpoints): Only make the overlays in edebug mode, so that we remove them when we exit.