Simplifies items in the Change request issue

This proposes some (significant) simplification updates to our current change template.

Summary

• Removes pre/post steps, I don't see much value in separating them out from the main steps. In the rare cases where we benefit from having pre/post, the technician can add them
• Adds copy/paste snippets for updating the change label
• Adds a new label ~change::aborted which we can add to track change issues that are rolled back or do not complete for tracking
• For the reviewer/technician checklist use a single checkbox instead of the rage-inducing multi-checkbox which requires a lot of patience
• Remove assignee and critical label requirement for the technician as that is done automatically now 99% of hte time via woodhouse