Reproduction Steps

1. Create a multibranch pipeline job, add 5-minute SCM polling as trigger to the pipeline configuration. Set source as a dummy SCM repository with multiple branches
2. Build multi-branch jobs, observe successful polling history and builds
3. Disable the multibranch job itself in the configuration
4. Observe polling history for branches continue even after job being disabled
5. Go into a branch build configuration page and observe that the pollscm option is greyed out cannot be disabled

Expected behaviour

The polling should not happen.