Test broken symlinks for subrepos are created during on_demand sync of kickstart trees
1. Sync kickstart tree with on_demand policy.
2. Switch to immediate policy and re-sync.
3. Note that subrepos (HighAvailability, Addons) have broken symlinklinks because Pulp doesn't support subrepos but it seems like symlinks are still created for those during on_demand sync.
That causes Pulp to Pulp sync to fail.
Pulp should not create symlinks for the unsupported parts of kickstart trees.