Update processes in deprecation issue template
What does this MR do and why?
Update processes in deprecation issue template
- Move checklists below information that users need to read.
- Remove "Removals" docs step; this page no longer exists.
- Move label quick actions to the relevant sections.
- Reference "GPM or Director" vs "GPM".
- Update handbook URLs for new domain.
MR acceptance checklist
This is a process change only—no MR acceptance checklist is required.