fix(multi-runner): route v1 and v2 runners separately

[edersonbrilhante]

Description

• Route v2 lanes through the provider-aware runner-config module.
• Keep stable v1 lanes on the legacy runners path and prevent the legacy module from being created for v2-only configuration.
• Expose v2 runner resources through runners_map_v2.
• Add routing assertions covering stable v1 and experimental v2 configurations.

Test Plan

• terraform fmt and git diff --check
• Terraform initialization and routing test coverage for modules/multi-runner
• Local provider-plugin handshake prevented a complete native-provider test run on macOS arm64

Related Issues

Depends on #5345.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None