🦙 Llama2 optimization with multi-ep managed env

[trajepl]

Describe your changes

1. Llama2 optimization with multi-ep
2. Add info-level log to tell the system creation time.
3. Use device and ep but not only device to determine the default value of use_gpu.

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• Lint and apply fixes to your code by running lintrunner -a
• Is this a user-facing change? If yes, give a description of this change to be included in the release notes.
• Is this PR including examples changes? If yes, please remember to update example documentation in a follow-up PR.

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[devang-ml]

We should just provide BandomdataWithKVCache as built-in data-config so that we do not need to keep copying this in user script in every example.

[trajepl]

Indeed, I have that in mind also there is work item to track it. Let us finish the build-in kv cache data config later.