This reduces a bit the coupling of the security dashboard's router and
store, and [removes the router from the Pipeline Security Dashboard][1].

Now, to sync a security dashboard to its router (as is done for the
Group and Project Security Dashboards), the router must be explictly
created and bound to the store using the `syncWithRouter` store plugin
at store creation.

[1]: https://gitlab.com/gitlab-org/gitlab/issues/32749