ol: Fix formatting in org-link--open-elisp

* lisp/ol.el (org-link--open-elisp): The %S token in the format string
causes the propertization to be printed as a structure, instead of
styling the path string.  This is clearly not the intended behaviour.

Reported by Omar Antolín Camarena <omar@matem.unam.mx>
in https://list.orgmode.org/87sft58b6r.fsf@matem.unam.mx

lisp/ol.el

@@ -1322,7 +1322,7 @@ PATH is the sexp to evaluate, as a string."
 	       (string-match-p org-link-elisp-skip-confirm-regexp path))
 	  (not org-link-elisp-confirm-function)
 	  (funcall org-link-elisp-confirm-function
-		   (format "Execute %S as Elisp? "
+		   (format "Execute %s as Elisp? "
 			   (org-add-props path nil 'face 'org-warning))))
       (message "%s => %s" path
 	       (if (eq ?\( (string-to-char path))