cloud/shepherd: rename shepherd.State to shepherd.Availability

Change-Id: I8e1fa243317bf4f97af98303b10b979b98943156
Reviewed-on: https://review.monogon.dev/c/monogon/+/2779
Reviewed-by: Serge Bazanski <serge@monogon.tech>
Tested-by: Jenkins CI
diff --git a/cloud/shepherd/mini/provider.go b/cloud/shepherd/mini/provider.go
index 42b6348..eb6fc08 100644
--- a/cloud/shepherd/mini/provider.go
+++ b/cloud/shepherd/mini/provider.go
@@ -38,8 +38,8 @@
 	return d.Address
 }
 
-func (d machine) State() shepherd.State {
-	return shepherd.StatePossiblyUsed
+func (d machine) Availability() shepherd.Availability {
+	return shepherd.AvailabilityPossiblyUsed
 }
 
 func (p *provider) ListMachines(ctx context.Context) ([]shepherd.Machine, error) {