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/manager/provisioner_test.go b/cloud/shepherd/manager/provisioner_test.go
index 5adc408..a145bdc 100644
--- a/cloud/shepherd/manager/provisioner_test.go
+++ b/cloud/shepherd/manager/provisioner_test.go
@@ -88,8 +88,8 @@
 func TestProvisioner_resolvePossiblyUsed(t *testing.T) {
 	const providedMachineID = "provided-machine"
 
-	providedMachines := map[shepherd.ProviderID]bool{
-		providedMachineID: true,
+	providedMachines := map[shepherd.ProviderID]shepherd.Machine{
+		providedMachineID: nil,
 	}
 
 	tests := []struct {