Move the unit context to a name matching the other contexts. Remove some
unnecessary entries from it that are unused, and remove references to
the old name relying on spec helper to load all contexts.
Switch to instance doubles for driver where possible and reduce usage of
allow_any_instance_of.
Additionally replace some incorrect allows with expects to validate
calls are not made.
Adjust handling to use a method reference instead of attempting to
update the env value as that only appears to be available to actions
further down the chain and any changes are not visible during recovery
when exercised for real.
By passing a function reference can limit the actions that can be taken
to only allow a single call that will set a flag internal to the clean
up action.
Fixes: #1328
Switch to dedicated actions to trigger destroy/halt via the recovery
mechanism if the VM bring up has failed to complete the bring up of the
machine.
Fixes: #1328
