This change adds support for node retirement: nodes can
have additional properties 'retired' and 'retired_reason'
which change the way the nodes (can) traverse the FSM
and which operations are allowed. In particular:
- retired nodes cannot move from manageable to available;
- upon instance deletion, retired nodes move to manageable
(rather than available).
Story: #2005425
Task: #38142
Change-Id: I8113a44c28f62bf83f8e213aeb6704f96055d52b
3ecaadbb35