Adjust node max-http-header-size setting

[bdehamer]

Closes: #606

When using the push-to-registry option some users have encountered header overflow issues when interacting with certain OCI registries.

By default, node limits the total size of headers received in a single response to 16KB. We have seen certain interactions with the Google Artifact Registry API return headers totaling 21KB.

This change updates the maximum allowed header size to 32KB in order to give us some more breathing room when interacting with these registries.

[Copilot]

Pull Request Overview

This PR increases the Node.js HTTP header size limit from the default 16KB to 32KB to resolve header overflow issues when using the push-to-registry option with certain OCI registries, particularly Google Artifact Registry.

• Adds NODE_OPTIONS environment variable with --max-http-header-size=32768 to the attest action step

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