Refactor dockerfiles and deprecate stable_stack and jax_ai_image mode

[SurbhiJainUSC]

Description

• Refactor docker_build_dependency_image.sh and delete unnecessary docker build modes
• Deleted unused Dockerfiles: maxtext_jax_ai_image.Dockerfile, jetstream_pathways.Dockerfile, maxengine_server.Dockerfile, maxtext_db_dependencies
• Updated relevant documentation & Github tests
• Fixes: b/446945869

TODO: Deprecate maxtext_custom_wheels.Dockerfiles once tpu-recipes are migrated to use stable/nightly mode

Tests

https://paste.googleplex.com/4931634182881280

Checklist

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• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[richjames0]

lgtm