karmada: Don't auto distribute custom namespace which karmada component is deployed

What happened:

I installed karmada on the demo namespace, when adding a cluster, the demo namespace is automatically created by karmada namespace controlleron all member clusters.

karmada ns list (when karmada deploy demo ns):

NAME                     STATUS   AGE
default                  Active   123d
karmada-cluster          Active   114d
karmada-es-dev           Active   27h
demo                     Active   123d

What you expected to happen:

I just want to deploy karmada components on the demo namespace, but don’t want to distribute the demo namespace by default.

We should allow users to choose whether to distribute the demo namespace, rather than depending on where the karmada components are deployed.

karmada ns list (when karmada deploy any ns):

NAME                     STATUS   AGE
default                  Active   123d
karmada-cluster          Active   114d
karmada-system           Active   123d

How to reproduce it (as minimally and precisely as possible):

deploy karmada on custom namespace

/cc @RainbowMango @lonelyCZ @prodanlabs @JarHMJ @likakuli

/assign