refactor(runner-providers): resolve labels for runners

[edersonbrilhante]

Description

• Rename the scale-up provider hook from prepareGroup to resolveLabelsForRunners.
• Replace PreparedScaleUpRunnerGroup with RunnerLabelResolution, containing the resolved runnerLabels and provider-specific state.
• Update control-plane orchestration, the EC2 provider, the provider template, registry expectations, and existing tests in place.
• Preserve runtime behavior while making the plugin contract explicit: message labels are resolved into runner labels and state used for runner lookup and creation.

Test Plan

• Control-plane suite: 14 test files / 326 tests passed
• Runner-provider suite: 10 test files / 270 tests passed
• ESLint and Prettier passed for all changed files
• Exact test-title inventory: 276 before and after, with no additions or removals
• git diff --check

Local TypeScript build validation remains blocked by the installed @aws-sdk/client-ec2 declarations missing exports used throughout the existing EC2 sources; the same environment issue affects untouched code.

Related Issues

Stacked on #5248

[github-actions]

Dependency Review

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

Scanned Files

None