ci: move unit tests to GitHub Actions and optimize Azure Pipelines

[Carter Tinney (cartertinney)]

Thank you for helping us improve the Azure IoT Python SDK!

Checklist

• I have read the contribution guidelines.
• Existing test coverage and every test matrix leg are preserved.
• No public API behavior is changed.

Reference/Link to the issue solved with this PR (if any)

N/A

Description of the problem

Portable checks currently run in Azure Pipelines alongside resource-dependent and Microsoft compliance jobs. This increases ADO usage and leaves several live-resource pipelines doing avoidable checkout, dependency download, provisioning, and duplicate-trigger work.

Description of the solution

• Move Ruff and the unchanged Python 3.10-3.14 unit-test matrix to GitHub Actions.
• Keep CodeQL, Component Governance, package publication, and all unique E2E matrices in ADO.
• Add Dependabot updates for SHA-pinned GitHub Actions.
• Cache uv downloads and skip unnecessary setup/cleanup checkouts in ADO.
• Generate resource names without installing uuid.
• Create consumer groups with bounded concurrency and run independent DPS/IoT Hub creation concurrently.
• Use full existing matrix concurrency, migrate canary legs from retired Ubuntu 20.04, mask secret outputs, and remove environment dumps.
• Scope Horton triggers to main pushes and PRs targeting main to avoid duplicate source-branch runs.

Resource deletion remains synchronous so pipeline success still confirms that Azure finished deleting the resource group.

Validation

• Parsed all ADO and GitHub workflow YAML.
• Syntax-checked modified inline Bash blocks with bash -n.
• Mechanically verified that pytest commands and matrix legs are unchanged, except for the approved canary runner-image migration.
• Ran Ruff and package builds locally.

This is a draft PR to evaluate CI correctness, queue behavior, and elapsed time before marking it ready for review.