Unify Special:Contribs/DeletedContribs subtitle implementation

Unify Special:Contribs/DeletedContribs subtitle implementation

Basically all of the code was duplicated, except that Contribs had a
link to DeletedContribs, and DeletedContribs had a link to Contribs.

Now DeletedContribs will call the function in Contribs, and remove the
DeletedContribs link, and add its own link to Contribs instead of
needing to duplicate the entire list of links.

Change-Id: Ia004a4a69427fd5b554131b19b0e263523b7da67