fix(ci): keep owner workflow generation self-hosted and stable

[artiphishle]

Summary

• render Devtools owner workflows with the built APM and structure CLIs instead of falling back to package-local binaries;
• normalize rendered workflow output to exactly one terminal newline, including when the optional PKGViz audit is omitted;
• add regression coverage for both behaviors.

Architecture

The normal managed-workflow path already resolves self-hosted Devtools commands. This change makes the Renovate owner-sync path use the same owner-aware command resolution instead of adding a compatibility path or CI exception.

Validation

CI will run the canonical repository validation on this PR.

Closes #261.
Related: #241, #242.