fix(macrobenchmarks): use random optimizer moments, not zeros, in CPU sim

[zhixiangli]

This pull request updates the _materialize_adamw_state function in the Llama 3.1 8B CPU simulation benchmark to initialize AdamW optimizer states with random values instead of zeros, preventing trivial data compression and ensuring realistic IO benchmark results. I have no feedback to provide as there are no review comments.

[gemini-code-assist]

Code Review

This pull request updates the _materialize_adamw_state function in the Llama 3.1 8B CPU simulation benchmark to initialize AdamW optimizer states with random values instead of zeros, preventing trivial data compression and ensuring realistic IO benchmark results. I have no feedback to provide as there are no review comments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.68%. Comparing base (1b08827) to head (e2ecb09).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #949   +/-   ##
=======================================
  Coverage   89.68%   89.68%           
=======================================
  Files          16       16           
  Lines        3579     3579           
=======================================
  Hits         3210     3210           
  Misses        369      369           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[yuxin00j]

nit: remove the last sentence in the PR description?