A new create_timeout attribute was added that had some backwards
incompatibilities, and as per discussion in #10823, it was determined we
could make upgrading to 0.8.x easier by fixing them, without really
losing any functionality.
Because create_timeout is not something stored or transmitted to the
API, it's not something we need a ForceNew on. Also, because an update
wouldn't result in an API call, we can add a state migration to avoid a
false positive diff that requires people to plan and apply but doesn't
actually make an API call.
It doesn't need to be a List of Maps, it can just be a Map.
We're also safe to remove a previous workaround I stuck in there.
The config parsing is equivalent between a list of maps and a plain map,
so we just need a state migration to make this backwards compatible.
Paddy