OWNERS: SIG Release leadership transition and Release Manager updates
OWNERS: SIG Release leadership transition and Release Manager updates

- Promote Adolfo to full-fledged Release Manager
- Add Arnaud as Release Manager Associate
- Tim, Hannes, and Doug retire as Release Managers
- Tim is now Emeritus Chair
  ...but remains as subproject owner for a few things!
- Dan joins as SIG TL (and by extension subproject owner)
- Sascha moves from TL to Chair
- Grant Lauri approval powers as SIG Program Manager

Signed-off-by: Stephen Augustus <f96984fef9637085f0559f1484dfd4e99545cd6e@vmware.com>

kubernetes/sig-release