profile-controller: Support custom cluster domain other than cluster.local

[avintonOfficial]

profile controller does not work on the clusters which have a custom cluster domain because of the hardcoded "Principals".

• https://github.com/kubeflow/kubeflow/blob/master/components/profile-controller/controllers/profile_controller.go#L466-L472

Original code:

				From: []*istioSecurity.Rule_From{
					{
						Source: &istioSecurity.Source{
							Principals: []string{"cluster.local/ns/kubeflow/sa/notebook-controller-service-account"},
						},
					},
				},

This PR adds support for arbitrary cluster domains by using the CLUSTER_DOMAIN environment variable.
The environment variable CLUSTER_DOMAIN is optional, so the profile controller uses "cluster.local" as is when not set.

Kindly review this PR.

[kimwnasptd]

/lgtm
/approve

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kimwnasptd

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