[CI] This PR enhances testing of the CI procedures on both v6e and v7x.

[dennisYehCienet]

Description

This PR introduces placeholders into the YML files to enable the use of different variables for both v6e and v7x during the upload of CI procedures. This applies to both pipeline_jax.yml and main.yml.

FYI, the new procedure covers the pipeline_jax_tpu7x.yml, so the original file has been removed.

Tests

buildkite (test few main.yml and pipeline_jax.yml)

Checklist

Before submitting this PR, please make sure:

• I have performed a self-review of my code.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have made or will make corresponding changes to any relevant documentation.

[github-actions]

Description

Start with a short description of what the PR does and how this is a change from
the past.

The rest of the description includes relevant details and context, examples:

• why is this change being made,
• the problem being solved and any relevant context,
• why this is a good solution,
• some information about the specific implementation,
• shortcomings of the solution and possible future improvements.

If the change fixes a Github issue, please include a link, e.g.,:
FIXES: #123456

Tests

Please describe how you tested this change, and include any instructions and/or
commands to reproduce.

Checklist

Before submitting this PR, please make sure:

• I have performed a self-review of my code.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have made or will make corresponding changes to any relevant documentation.