These procedures were already either undocumented (and de facto
deprecated) or documented as deprecated or redundant.
* gnu/services/base.scm (guix-service, guix-publish-service): Mark as
deprecated.
* gnu/services/mcron.scm (mcron-service): Likewise.
* gnu/services/networking.scm (tor-service): Likewise.
* doc/guix.texi (Scheduled Job Execution): Remove 'mcron-service' and
adjust example.
(Networking Services): Remove 'tor-service'.
* gnu/tests/base.scm (%mcron-os): Use 'mcron-service-type' instead of
'mcron-service'.
* gnu/tests/networking.scm (%tor-os): Use 'tor-service-type' instead of
'tor-service'.
* tests/guix-system.sh: Likewise.
