[SPARK-53852] Add spark.kubernetes.driver.pod.excludedFeatureSteps usage example

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR aims to add spark.kubernetes.driver.pod.excludedFeatureSteps usage example.

Why are the changes needed?

Since Apache Spark K8s Operator v0.6.0, we can use new features from Apache Spark 4.1.0-preview2.

• [SPARK-53787] Upgrade Spark to 4.1.0-preview2 #364

For example, spark.kubernetes.driver.pod.excludedFeatureSteps allows us to skip the specific feature steps. If we set the following, we can skip KerberosConfDriverFeatureStep which fails always on Java 25 environment currently.

• [SPARK-52830][K8S] Support spark.kubernetes.(driver|executor).pod.excludedFeatureSteps spark#51522

spark.kubernetes.driver.pod.excludedFeatureSteps: "org.apache.spark.deploy.k8s.features.KerberosConfDriverFeatureStep"

BEFORE

25/10/09 04:22:23 INFO pi-preview default o.a.s.i.Logging You have not specified a krb5.conf file locally or via a ConfigMap. Make sure that you have the krb5.conf locally on the driver image.
WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::loadLibrary has been called by org.apache.hadoop.util.NativeCodeLoader in an unnamed module (file:/opt/spark-operator/operator/spark-kubernetes-operator.jar)
WARNING: Use --enable-native-access=ALL-UNNAMED to avoid a warning for callers in this module
WARNING: Restricted methods will be blocked in a future release unless native access is enabled

25/10/09 04:22:23 WARN pi-preview default o.a.h.u.NativeCodeLoader Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
25/10/09 04:22:23 WARN pi-preview default o.a.s.i.Logging Fail to get credentials
java.lang.UnsupportedOperationException: getSubject is not supported
	at java.base/javax.security.auth.Subject.getSubject(Subject.java:277)
	at org.apache.hadoop.security.UserGroupInformation.getCurrentUser(UserGroupInformation.java:588)
	at org.apache.spark.deploy.k8s.features.KerberosConfDriverFeatureStep.liftedTree1$1(KerberosConfDriverFeatureStep.scala:95)

AFTER

25/10/09 04:20:34 INFO pi-preview default o.a.s.i.Logging You have not specified a krb5.conf file locally or via a ConfigMap. Make sure that you have the krb5.conf locally on the driver image.

Does this PR introduce any user-facing change?

No. This is an example update.

How was this patch tested?

Manual review.

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

No.

[dongjoon-hyun]

Thank you, @viirya . Merged to main.