LeaderElectionID should be unique (#479)

Running several Cluster API pods (e.g. CAPI + CABPK + an infra provider)
in the same namespace results in leader election errors.

This PR added the leader election ID.

Also, fixed a go mod problem for kustomize

Author: jichenjc

Makefile

@@ -101,7 +101,7 @@ ifndef HAS_YQ
 endif
 ifndef HAS_KUSTOMIZE
 	echo "installing kustomize"
-	go get sigs.k8s.io/kustomize/v3/cmd/kustomize
+	GO111MODULE=off go get sigs.k8s.io/kustomize/kustomize
 endif
 ifndef HAS_ENVSUBST
 	echo "installing envsubst"

main.go

@@ -135,6 +135,7 @@ func main() {
 		Scheme:             scheme,
 		MetricsBindAddress: metricsAddr,
 		LeaderElection:     enableLeaderElection,
+		LeaderElectionID:   "controller-leader-election-capo",
 		SyncPeriod:         &syncPeriod,
 		Namespace:          watchNamespace,
 	})