[SPARK-49148] Use the latest PMD 6.x rules instead of the deprecated ones

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR aims to use the latest PMD 6.x rules instead of the deprecated ones.

Why are the changes needed?

There are 204 warnings from PMD like the following. We had better fix it before we do the release.

• https://github.com/apache/spark-kubernetes-operator/actions/runs/10290307906/job/28479975975

Use Rule name category/java/errorprone.xml/BrokenNullCheck instead of the deprecated Rule name rulesets/java/basic.xml/BrokenNullCheck. PMD 7.0.0 will remove support for this deprecated Rule name usage.

$ ./gradlew clean build | grep PMD | wc -l
     204 

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Pass the CIs and check the CI link.

Or, manually check.

$ ./gradlew clean build | grep PMD | wc -l
       0

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

No.

[dongjoon-hyun]

cc @viirya , @jiangzho

[dongjoon-hyun]

Thank you, @viirya ! Merged to main.