Revert "org.el: Include tags from `org-tag-alist' when completing with the TAB key."

This reverts commit 647396464d563634b980127673cf61769663407e.

lisp/org.el

@@ -13726,10 +13726,9 @@ Returns the new tags string, or nil to not change the current settings."
 		  (condition-case nil
 		      (setq tg (org-icompleting-read
 				"Tag: "
-				(append (or buffer-tags
-					    (with-current-buffer buf
-					      (org-get-buffer-tags)))
-					(mapcar 'car table))))
+				(or buffer-tags
+				    (with-current-buffer buf
+				      (org-get-buffer-tags)))))
 		    (quit (setq tg "")))
 		  (when (string-match "\\S-" tg)
 		    (add-to-list 'buffer-tags (list tg))