fix: Add default values for namespaces to match usage descriptions

[snappyyouth]

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Purpose of this PR

Provide a clear and concise description of the changes. Explain the motivation behind these changes and link to relevant issues or discussions.

Proposed changes:

• Add default values for namespaces to match usage descriptions
• Remove incorrect cache settings

Change Category

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• [ √ ] Bugfix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that could affect existing functionality)
• Documentation update

Rationale

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• [ √ ] I have conducted a self-review of my own code.
• I have updated documentation accordingly.
• I have added tests that prove my changes are effective or that my feature works.
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Additional Notes

[snappyyouth]

In the controller-runtime, program will select newMultiNamespaceCache or NamespaceAllCache By the length of the namespace.
https://github.com/kubernetes-sigs/controller-runtime/blob/c50f2dfd0b618220108d320e3e690340a9246a75/pkg/cache/cache.go#L315

But now,when i want to use NamespaceAllCache,spark-operator will add a superfluous cache. it caused the following error.

2024-08-14T17:33:02.865+0800 ERROR sparkapplication/controller.go:659 Failed to reconcile SparkApplication {"name": "spark-pi-3ww", "namespace": "spark-operator", "error": "failed to get pods for SparkApplication spark-operator/spark-pi-3ww: unable to list: spark-operator because of unknown namespace for the cache"} github.com/kubeflow/spark-operator/internal/controller/sparkapplication.(*Reconciler).reconcileFailedSparkApplication /opt/workproject/spark-operator/internal/controller/sparkapplication/controller.go:659 github.com/kubeflow/spark-operator/internal/controller/sparkapplication.(*Reconciler).Reconcile /opt/workproject/spark-operator/internal/controller/sparkapplication/controller.go:193 sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile /root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.17.5/pkg/internal/controller/controller.go:119 sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler /root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.17.5/pkg/internal/controller/controller.go:316 sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem /root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.17.5/pkg/internal/controller/controller.go:266 sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2 /root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.17.5/pkg/internal/controller/controller.go:227 2024-08-14T17:33:02.865+0800 ERROR controller/controller.go:329 Reconciler error {"controller": "spark-application-controller", "namespace": "spark-operator", "name": "spark-pi-3ww", "reconcileID": "3cd58a57-4191-4854-8bf2-bfdc5eaea28c", "error": "failed to get pods for SparkApplication spark-operator/spark-pi-3ww: unable to list: spark-operator because of unknown namespace for the cache"} sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler /root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.17.5/pkg/internal/controller/controller.go:329 sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem /root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.17.5/pkg/internal/controller/controller.go:266 sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2 /root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.17.5/pkg/internal/controller/controller.go:227

[ChenYi015]

Thanks @snappyyouth for raising this PR and reporting the issue. I also encountered the same issue when I attempted to set spark.jobNamespaces to [""], and I am already working on it in PR #2123 .

[snappyyouth]

谢谢@snappyyouth提出此 PR 并报告问题。我在尝试设置spark.jobNamespaces为时也遇到了同样的问题[""]，并且我已经在 PR #2123中处理此问题。
I am new to the open source world, what should I do next? Invite a second person to lgtm?

[ChenYi015]

@snappyyouth Thanks for the contribution. Let us wait for another maintainer to approve the CI workflow and lgtm, if the integration test runs successfully, then this PR will be merged.
/assign @yuchaoran2011 @vara-bonthu @andreyvelich

[vara-bonthu]

Thanks for the fix @snappyyouth 🙌🏼
/lgtm

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ChenYi015, vara-bonthu

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