[SPARK-53639] Use spark consistently for release-name of Helm installation

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR aims to use spark consistently for release-name of Helm installation.

Why are the changes needed?

Although we use spark in README.md and website like the following, old legacy names still exist.

spark-kubernetes-operator/README.md

Line 49 in cfd5063

helm install spark -f build-tools/helm/spark-kubernetes-operator/values.yaml build-tools/helm/spark-kubernetes-operator/

We need to unify this. Otherwise, INSTALLATION FAILED occurs due to the mismatch of meta.helm.sh/release-name.

$ helm install sparkx --create-namespace -f build-tools/helm/spark-kubernetes-operator/values.yaml build-tools/helm/spark-kubernetes-operator/
Error: INSTALLATION FAILED: Unable to continue with install: ServiceAccount "spark-operator" in namespace "default" exists and cannot be imported into the current release: invalid ownership metadata; annotation validation error: key "meta.helm.sh/release-name" must equal "sparkx": current value is "spark"

Does this PR introduce any user-facing change?

No for the clean installations.

For the users who have the existing installation, they need to remove old K8s objects before installation.

How was this patch tested?

Pass the CIs.

Was this patch authored or co-authored using generative AI tooling?

No.

[dongjoon-hyun]

Thank you, @peter-toth .

[dongjoon-hyun]

cc @jiangzho , too.

[dongjoon-hyun]

Merged to main.