[TON-743] Add managed DatadogAgent settings to the EKS add-on chart

[fanny-jiang]

What does this PR do?

Adds managed DatadogAgent lifecycle settings and Kubernetes resources to the Datadog Operator EKS add-on chart.

Motivation

After installing the Operator EKS add-on, the EKS instrumenter needs a chart contract for requesting DatadogAgent creation and removal.

Additional Notes

This chart change is independent of credentials sync and add-on installation. It should be released after the Operator runtime support is available.

Minimum Agent Versions

• Agent: N/A
• Cluster Agent: N/A

Describe your test plan

• Parsed the Marketplace schema with jq.
• Linted, rendered, and packaged the wrapper chart with the pinned Operator dependency.

Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label
• All commits are signed (see: signing commits)

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Remove the duplicate secret schema key

This adds a second datadog-operator.apiKeyExistingSecret entry in the same JSON object, so parsers that accept duplicate keys keep this later string-only schema and discard the existing nullable/minLength definition above. In configurations that explicitly leave the chart default as null, validation now rejects a value that was previously allowed; keep the original definition or merge any intended changes into it.

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