Sync Environment Automation Roadmap with Project Tracker

Why is this change being made?

The goal of this MR is to update the roadmap to reflect what was actually worked on in a given milestone, including spillover epics from previous milestones. With this update, the roadmap will now be synced with the project tracker here: https://gitlab.com/groups/gitlab-com/gl-infra/-/epics/484#project-work.

Author Checklist

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