Fix test-org-element/cache "Preserve local structures when re-parenting."

* testing/lisp/test-org-element.el (test-org-element/cache): Add
spaces to make the "abcd" table a single table.  The old version uses
example org text with two tables and was passing because of another
bug in org-element-cache.  Testing the old version with
org-element-use-cache set to nil would yield error, while it should
not.

testing/lisp/test-org-element.el

@@ -3770,7 +3770,7 @@ Text
    (eq 'table
        (let ((org-element-use-cache t))
 	 (org-test-with-temp-text
-	     "#+begin_center\nP0\n\n<point>\n\n  P1\n  | a | b |\n| c | d |\n#+end_center"
+	     "#+begin_center\nP0\n\n<point>\n\n  P1\n  | a | b |\n  | c | d |\n#+end_center"
 	   (save-excursion (search-forward "| c |") (org-element-at-point))
 	   (insert "- item")
 	   (search-forward "| c |")