redhat_subscription: officially deprecate "autosubscribe" (#6646)
The "autosubscribe" alias for the "auto_attach" option has been
deprecated for many years, although only in the documentation.
Officially mark it as deprecated also in the module parameters spec,
slating it for removal in 9.0.0.
(cherry picked from commit 621bedf751)
Co-authored-by: Pino Toscano <ptoscano@redhat.com>
