[CI] why some MRs are running detached pipelines when that feature is not enabled for this project

Summary

We've noticed in #2976 (closed) ( !2238 (merged) ) that adding a job to existing pipeline triggered detached pipeline as described in Pipelines for merged results despite the fact that the feature is not enabled for the project directly.

Steps to reproduce

Create MR
modify pipeline adding "extra" job with no rules

Configuration used

Current behavior

observe detached pipeline being run that will include that job alone

Expected behavior

no detached pipelines since feature is not enabled

Versions

Chart: (tagged version | branch | hash git rev-parse HEAD)
Platform:
- Cloud: (GKE | AKS | EKS | ?)
- Self-hosted: (OpenShift | Minikube | Rancher RKE | ?)
Kubernetes: (kubectl version)
- Client:
- Server:
Helm: (helm version)
- Client:
- Server: