remove link to dead trac page

service.md

@@ -189,10 +189,9 @@ Those services have been retired.
 | oniongit      | test GitLab instance          | <https://oniongit.eu>             | hiro                | Eventually migrated to GitLab |
 | pipeline      | ?                             | <https://pipeline.torproject.org> | ?                   |                               |
 | [Prodromus][] | Web chat for support team     | <https://support.torproject.org>  | phoul, lunar, helix | ?                             |
-| [Trac][]      | Issues, wiki                  | <https://trac.torproject.org>     | hiro                | Migrated to GitLab, archived  |
+| Trac          | Issues, wiki                  | <https://trac.torproject.org>     | hiro                | Migrated to GitLab, archived  |
 | XMPP          | Chat/messaging                |                                   | dgoulet             | Abandoned for lack of users   |
 
-[Trac]: howto/trac
 [Prodromus]: https://github.com/rkallensee/prodromus
 [Atlas]: https://atlas.torproject.org