remove k8s NAT method

[macfarla]

PR description

K8s NAT method was deprecated in 24.10.0

Also removes this dependency 'io.kubernetes:client-java:21.0.1-legacy'

Fixed Issue(s)

Fixes #7533

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• Checked out our contribution guidelines?
• Considered documentation and added the doc-change-required label to this PR if updates are required.
• Considered the changelog and included an update if required.
• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

Locally, you can run these tests to catch failures early:

• spotless: ./gradlew spotlessApply
• unit tests: ./gradlew build
• acceptance tests: ./gradlew acceptanceTest
• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests

[macfarla]

@joshuafernandes any specific testing you want to see on this?

[joshuafernandes]

@joshuafernandes any specific testing you want to see on this?

All good @macfarla I'll be good to close this one out esp given the k8s APIs have long since changed. Thankyou!