pkg/operator/credentialsrequest: Safer resource version dereference

This should always be set for actual in-cluster resources, but isn't
set in some unit tests.  By using a local variable with safer
dereferencing, we avoid panics in
TestCredentialsRequestAzureReconcile/new_credential [1].

[1]: https://prow.ci.openshift.org/view/gs/test-platform-results/pr-logs/pull/openshift_cloud-credential-operator/812/pull-ci-openshift-cloud-credential-operator-master-unit/1872474465263161344#1:build-log.txt%3A65-85

pkg/operator/credentialsrequest/credentialsrequest_controller.go

@@ -808,11 +808,16 @@ func (r *ReconcileCredentialsRequest) Reconcile(ctx context.Context, request rec
 		cr.Status.LastSyncInfrastructureResourceVersion = infra.ResourceVersion
 	}
 
+	resourceVersion := "unset"
+	if infra != nil {
+		resourceVersion = infra.ResourceVersion
+	}
+
 	log.WithFields(log.Fields{
 		"NOT cloudCredsSecretUpdated":    cloudCredsSecretUpdated,
 		"NOT isStale":                    isStale,
 		"NOT isInfrastructureUpdated":    isInfrastructureUpdated,
-		"infraResourceVersion":           infra.ResourceVersion,
+		"infraResourceVersion":           resourceVersion,
 		"infraResourceVersionSynced":     cr.Status.LastSyncInfrastructureResourceVersion,
 		"name":                           cr.Name,
 		"hasRecentlySynced":              hasRecentlySynced,