Ensure we don't show warning when there are <1000 epics on a roadmap

We currently show this warning on roadmaps:

https://gitlab.com/groups/gitlab-com/-/roadmap?scope=all&utf8=%E2%9C%93&label_name[]=BT%20Roadmap

In that screenshot it's rendering for a label that only contains 51 total open Epics: https://gitlab.com/groups/gitlab-com/-/epics?scope=all&utf8=%E2%9C%93&state=opened&label_name[]=BT%20Roadmap

Let's review and ensure we're not rendering that warning if a user visits a board that is pre-filtered to a set of Epics that = <1k