Remove assert on ARCH_NAME in data collection step in workflows

[roseli-TT]

We would like to gradually remove reliance on ARCH_NAME env var.

Recently ARCH_NAME was removed from Galaxy demo pipelines. No tests need the env var set, but the data collection step in the workflow still has an assert on ARCH_NAME.

This PR removes the hard assert on ARCH_NAME in the data collection script and tries to infer from the runner name for CIv2 or the SKU config for CIv1.

Testing:

• Galaxy demo https://github.com/tenstorrent/tt-metal/actions/runs/21768966673

[Copilot]

Pull request overview

Removes the workflow’s hard dependency on ARCH_NAME by updating the benchmark environment data-collection code to infer device type from runner metadata (CIv2 runner naming) or repo config (CIv1 SKU config), and updates the Galaxy demo workflow to stop exporting ARCH_NAME.

Changes:

• Add device type inference logic (RUNNER_NAME / .github/sku_config.yaml) and remove the hard ARCH_NAME assert in benchmark environment JSON creation.
• Refactor repo-root path resolution used by benchmark artifact discovery.
• Comment out ARCH_NAME injection in the Galaxy demo workflow container environment.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
infra/data_collection/github/utils.py	Adds device-type inference and removes hard ARCH_NAME requirement for environment completion; refactors repo-root path usage.
.github/workflows/galaxy-demo-tests-impl.yaml	Stops exporting ARCH_NAME into the container environment for Galaxy demo jobs.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

[Copilot]

yaml.safe_load(f) can return None (e.g., empty YAML file), in which case config.get(...) will raise an AttributeError. Consider defaulting to an empty dict (e.g., config = yaml.safe_load(f) or {}) before accessing .get() to make the inference logic robust.

Suggested change

	config = yaml.safe_load(f)
	config = yaml.safe_load(f) or {}