chart: use release.namespace to specify target ns

[zwpaper]

What type of PR is this?

What this PR does / why we need it:

currently, we let users set the scheduler and controller namespace respectively in values.yaml, and only create the controller's namespace in templates.

but helm can manager namespace by --create-namespace and --namespace args,
we should leverage helm's namespace management ability.

this PR:

1. drop the controller namespace in templates
2. let helm to manager the target namespace by using .Release.Namespace
3. use the same namespace for the controller and secondary scheduler

Which issue(s) this PR fixes:

Fixes # #420

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Support custom namespace installation in Helm Chart

[k8s-ci-robot]

Hi @zwpaper. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[denkensk]

/ok-to-test

[Huang-Wei]

I verified in a kind 1.25 env:

⇒  helm install scheduler-plugins manifests/install/charts/as-a-second-scheduler/ --create-namespace --namespace foo
⇒  k get po -n foo
NAME                                            READY   STATUS    RESTARTS   AGE
scheduler-plugins-controller-58987f447f-jshdl   1/1     Running   0          39s
scheduler-plugins-scheduler-5756bc7f87-lzdj9    1/1     Running   0          39s
⇒  k get crd
NAME                                              CREATED AT
appgroups.appgroup.diktyo.k8s.io                  2023-03-03T01:21:25Z
elasticquotas.scheduling.sigs.k8s.io              2023-03-03T01:21:25Z
networktopologies.networktopology.diktyo.k8s.io   2023-03-03T01:21:25Z
noderesourcetopologies.topology.node.k8s.io       2023-03-03T01:21:25Z
podgroups.scheduling.sigs.k8s.io                  2023-03-03T01:21:25Z

[Huang-Wei]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Huang-Wei, zwpaper

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[nayihz]

Do we need to add some note in https://github.com/kubernetes-sigs/scheduler-plugins/blob/master/manifests/install/charts/as-a-second-scheduler/README.md#installing-the-chart ?

[zwpaper]

Hi @czybjtu, yes, we need the doc to be updated aligning with the new installation mechanism, it is appreciated that you found it, could you like to raise a PR for the update?