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The `propagateCorrelationID` option in Workhorse has been present since
gitlab-workhorse!529, but
the configuration option was never made available. This commit adds support
for enabling this option via:

```
gitlab_workhorse['propagate_correlation_id'] = true
```

This will enable us to support end-to-end tracing for HTTP requests.

Relates to:

1. gitlab#324836
2. gitlab-com/gl-infra/infrastructure#12798

Changelog: added