Remove Security Dashboard router from pipelines view
The Security Dashboard store is currently always instantiated with a router.
The Pipeline Security Dashboard, however, exists in a page with tabs that affect the URL. This means that after playing with the security dashboard's filters, and then changing tabs, you can end up with a URL like https://gitlab.com/gitlab-org/gitlab/pipelines/84217628/builds?severity=critical&confidence=high&report_type=dependency_scanning&page=1&days=90, which doesn't make much sense.
Rather than trying to make that play well with the security dashboard's router, it's easier to just not install our router there at all.
I would also argue that users are much less likely to want to link to a specific filtered list of vulnerabilities found in a particular pipeline than they would for a Group, Project or Instance, since a particular pipeline becomes stale and irrelevant pretty quickly.
So, let's make the router a configurable extra in the dashboard store, and only add it in at the Group, Project and Instance levels, and not the Pipelines (or future Merge Request) level.
This was brought up in !16738 (comment 221472914). Some initial work to make the security dashboard store more configurable has been done in !17250 (merged).