Remove post_training_local_dependencies.Dockerfile

[SurbhiJainUSC]

Description

• Delete maxtext_post_training_local_dependencies.Dockerfile
• Update Build Images Github workflow to only build nightly post-training docker image every day as post-training stable docker image will be build with a new pypi release Add job to build and upload docker image to pypi_release workflow #3369

Tests

N/A - cleanup

Checklist

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• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run end-to-end tests tests and provided workload links above if applicable.
• 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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