fix: skip instance workflow deployment in dataproduct config_source mode

When `config_source` is `"dataproduct"` (e.g. cog-ai), validation workflows are owned by the DataProduct sync pipeline. `deploy_validation_infrastructure` was still calling `deploy_instance_workflows` in that path, causing redundant workflow deployments that conflict with the sync pipeline.

## Bump

- [ ] Major
- [ ] Minor
- [x] Patch

## Changelog

### Fixed
- `deploy_validation_infrastructure` no longer deploys instance workflows when `config_source` is `"dataproduct"` — in that mode workflows are managed by the DataProduct sync pipeline
