Revert "ox: Change label naming scheme"

This reverts commit cf7d64f1e456cad281674fc81a8074f969b7911c.

lisp/ox.el

@@ -4149,18 +4149,9 @@ alphanumeric characters only."
 		     h))))
     (or (gethash datum cache)
 	(puthash datum
-		 (format "%s:%d"
+		 (format "org%s%d"
 			 (if type
-			     (case type
-			       (headline "sec")
-			       (paragraph
-				(if (org-element-property :caption datum)
-				    "fig" "paragraph"))
-			       (latex-environment "eq")
-			       (table "tbl")
-			       (otherwise
-				(replace-regexp-in-string "-" ""
-							  (symbol-name type))))
+			     (replace-regexp-in-string "-" "" (symbol-name type))
 			   "secondarystring")
 			 (incf (gethash type cache 0)))
 		 cache))))