Update harness to simplify 25.9.0 compatibility

[charlesbluca]

Description

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• If adjusting docker-compose.yaml environment variables have you ensured those are mimicked in the Helm values.yaml file.

[jdye64]

@charlesbluca is this still valid after a month? Still needed? If so feel free to merge otherwise feel free to close

[charlesbluca]

Now that we're not in 25.9 troubleshooting land, don't think we need to commit to holding on to this compat code