Adding back building images with mode=stable

[parambole]

Description

The flow to build maxtext with mode=stable was removed. This PR adds it back.

Tests

Ran the command locally

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• I have performed a self-review of my code.
• 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.

[yangyuwei]

Thanks Param for the fix!