Remove hard coded logger dev mode

Before this commit, the cluster operator always used a logger dev mode,
even in production.

After this commit, the logger is prod mode by default.

When developing locally deploying the operator using `make deploy-dev` and
`make deploy-kind`, the logger will use dev mode.

Futhermore, users can now configure more zap flags (see
https://github.com/kubernetes-sigs/controller-runtime/blob/66537ca5b7439b06f2f3b08901640f934834c9a1/pkg/log/zap/zap.go#L227-L233)
For example, they can set the log level.

Author: ansd

config/default/overlays/dev/manager_image_patch.yaml

@@ -17,3 +17,4 @@ spec:
       - image: ((operator_docker_image))
         name: operator
         imagePullPolicy: Always
+        args: ["--zap-devel"]

config/default/overlays/kind/manager_image_patch.yaml

@@ -17,3 +17,4 @@ spec:
       - image: ((operator_docker_image))
         name: operator
         imagePullPolicy: IfNotPresent
+        args: ["--zap-devel"]

main.go

@@ -45,9 +45,13 @@ func init() {
 func main() {
 	var metricsAddr string
 	flag.StringVar(&metricsAddr, "metrics-addr", ":12345", "The address the metric endpoint binds to.")
+
+	opts := zap.Options{}
+	opts.BindFlags(flag.CommandLine)
+
 	flag.Parse()
 
-	ctrl.SetLogger(zap.New(zap.UseDevMode(true)))
+	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
 
 	operatorNamespace := os.Getenv("OPERATOR_NAMESPACE")
 	if operatorNamespace == "" {