JENKINS-74950 - Improve the K8s Maven sample to run in resources limited environments

[jgarciacloudbees]

JENKINS-74950 - Improve the K8s Maven sample to run in resources limited environments

The sample "kubernetes-maven.groovy" does not specify any request or limit.

In resource limited environments it could fail due to OOM events.

We have reproduced this issue by running it in a pod with memoty limited to 256Mi.

We have modified the current sample to add requests and limits for memory.

spec:
  containers:
  - resources:
      requests:
        memory: "256Mi"
      limits:
        memory: "512Mi" 

Testing done

Manual test have been performed to confirm the script works properly in limited environments that was failing with the original sample.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
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• Ensure you have provided tests - that demonstrates feature works or fixes the issue