cloud/shepherd: skip machines in failed state

Currently we are not ignoring machines that are in failed state, which
brings the provider to a stop as soon as a provision request fails. We
should ignore such machines.

Change-Id: I7be64c710cc15428f4d8d4e75b6df1e816d453f8
Reviewed-on: https://review.monogon.dev/c/monogon/+/2417
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 05b628f..42b6348 100644
--- a/cloud/shepherd/mini/provider.go
+++ b/cloud/shepherd/mini/provider.go
@@ -26,6 +26,10 @@
 	Location   string              `json:"Location"`
 }
 
+func (d machine) Failed() bool {
+	return false
+}
+
 func (d machine) ID() shepherd.ProviderID {
 	return d.ProviderID
 }