[17.0] Deploy:Environments deprecations/removals
- What are we going to remove?
- Any planned breaking changes?
- Any cleanups of old compatibility code?
DRI: @timofurrer
DRI for last 2 weeks: @hustewart
**Board**: [17.0 Group Environments Deprecations & Removals](https://gitlab.com/groups/gitlab-org/-/boards/7266052?group_by=epic)
epic