legacy: bibindex admin interface fix

* Fixes bibindex admin interface. (closes #2190)

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
legacy: legacy admin interfaces addition

* Adds all the admin interfaces to the `/admin` page.

Co-authored-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>