feat(examples): add multi-runner-v2 example

[edersonbrilhante]

Description

• Add a multi-runner-v2 example using the experimental v2 global and per-lane configuration variables.
• Demonstrate shared defaults and three lanes with v2-owned matcher, lifecycle, and AWS compute settings.
• Remove the stable v1 compatibility arguments now that fix(multi-runner): make v2 inputs independent #5368 makes them optional for v2.
• Add the example to the Terraform verification matrix and documentation navigation.

Test Plan

• terraform init -backend=false -input=false completed for examples/multi-runner-v2.
• terraform validate passed for the v2 example after removing the legacy arguments.
• Terraform formatting and git diff --check passed.
• Repository commit hooks passed Terraform formatting, validation/TFLint, and merge-conflict checks.

Related Issues

Depends on #5368, which depends on #5346

[github-actions]

Dependency Review

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

Scanned Files

None