Remove created and last updated sorting options from epic roadmap
Background
In https://gitlab.com/gitlab-org/gitlab-ee/issues/7325 there is the challenge of loading epics on scroll and inserting them in the right sorting order.
When discussing this, we noticed that the “Created date” and “Last updated” sorting options might not make much sense to have in the epic roadmap view. The roadmap view is used to situate epics in time, where their creation/update date don't matter. Not only that, but the roadmap view only shows epics that have start and/or due date. So why would one prefer to see the roadmap by Created or Updated date?
https://gitlab.com/gitlab-org/gitlab-ee/issues/8933 will decouple the sorting of the epic roadmap from the epic list. This can be an improvement after that.
Proposal
Remove the “Created date” and “Last updated” sorting options.