Consolidate A100 CUDA CI jobs into shared batch runners

[Gasoonjia]

Summary:
Collapse the four A100 runners (per-model export + e2e for the two A100-only models) into two shared single-runner batch jobs driven by a shared config file. Each model is processed independently with per-model pass/fail reporting; a job is green only if all its models pass, and one model's failure never blocks another.

• Add .ci/scripts/cuda_a100_models.txt: shared source of truth for which models need an A100 runner (one line per model).
• Add .ci/scripts/export_model_artifact_batch.sh: loops the config, delegates to export_model_artifact.sh per model under set +e, writes per-model _status files + logs, prints a summary section (stdout + GITHUB_STEP_SUMMARY), emits ::error:: annotations, exits non-zero if any model failed.
• Add .ci/scripts/test_model_e2e_batch.sh: runs install_requirements.sh once, reads each model's export status (skips with surfaced error if export failed), delegates to test_model_e2e.sh per model, prints the same style of summary, exits non-zero unless every model fully passed.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/19922

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 1 Cancelled Job, 3 Unclassified Failures

As of commit c38e2ba with merge base 4469d84 ():

UNCLASSIFIED FAILURES - DrCI could not classify the following jobs because the workflow did not run on the merge base. The failures may be pre-existing on trunk or introduced by this PR:

• Test CUDA Builds / export-models-cuda-a100 / linux-job (gh) (this job did not run on the merge base, so DrCI cannot tell whether the failure is pre-existing)
• Test CUDA Builds / test-model-cuda-e2e (mistralai, Voxtral-Mini-4B-Realtime-2602, quantized-int4-tile-packed) / linux-job (gh) (this job did not run on the merge base, so DrCI cannot tell whether the failure is pre-existing)
  RuntimeError: Command docker exec -t 1e778cce4bb828dce7d4c1c81616af0d46d886f21adc0c8c7eefd3dbfdbbdcae /exec failed with exit code 1
• Test CUDA Builds / test-models-cuda-a100-e2e / linux-job (gh) (this job did not run on the merge base, so DrCI cannot tell whether the failure is pre-existing)
  Unable to download artifact(s): Artifact not found for name: cuda-a100-models

CANCELLED JOB - The following job was cancelled. Please retry:

• trunk / test-arm-backend-ethos-u (test_smaller_stories_llama) / linux-job (gh)

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[linux-foundation-easycla]

• ❌ The email address for the commit (c38e2ba) is not linked to the GitHub account, preventing the EasyCLA check. Consult this Help Article and GitHub Help to resolve. (To view the commit's email address, add .patch at the end of this PR page's URL.) For further assistance with EasyCLA, please visit our EasyCLA portal and chat with our support bot.

[github-actions]

This PR needs a release notes: label

If your change should be included in the release notes (i.e. would users of this library care about this change?), please use a label starting with release notes:. This helps us keep track and include your important work in the next release notes.

To add a label, you can comment to pytorchbot, for example
@pytorchbot label "release notes: none"

For more information, see
https://github.com/pytorch/pytorch/wiki/PyTorch-AutoLabel-Bot#why-categorize-for-release-notes-and-how-does-it-work.