ci: publish and deploy sam-console to GKE testnet

[aojea]

No description provided.

[gemini-code-assist]

Code Review

This pull request updates the sam-console image source to a specific container registry and modifies the SAM_ADMIN_TOKEN secret reference to be environment-specific. The reviewer recommends using a variable for the image registry prefix instead of hardcoding it to maintain flexibility across different deployment environments.

[gemini-code-assist]

Hardcoding the image registry ghcr.io/google/ reduces this template's flexibility. It's better to use a variable for the image prefix to allow this template to be used with different container registries across various environments (e.g., local development, testing, production).

You could reintroduce the ${IMAGE_PREFIX} variable and set it to ghcr.io/google/ in your GKE testnet CI/CD pipeline. For other environments like local development, it could be left empty to use local images.

        image: ${IMAGE_PREFIX}sam-console:${IMAGE_TAG}