Fix environment recovery

As the environment is no longer stored in the meta information,
Poseidon wasn't able to recover environments. It expected the
environment id to be found in the meta data. We now recover
the environment id from the job id.

runner/manager.go

@@ -355,3 +355,11 @@ func IsEnvironmentTemplateID(jobID string) bool {
 	parts := strings.Split(jobID, "-")
 	return len(parts) == 2 && parts[0] == nomad.TemplateJobPrefix
 }
+
+func EnvironmentIDFromTemplateJobID(id string) (string, error) {
+	parts := strings.Split(id, "-")
+	if len(parts) < 2 {
+		return "", fmt.Errorf("invalid template job id: %w", ErrorInvalidJobID)
+	}
+	return parts[1], nil
+}