User sees shared pipelines in Private section in Central Dashboard while not being a contributor in any namespace

[furiousassault]

/kind bug

What steps did you take and what happened:
[A clear and concise description of what the bug is.]
We have a Kubeflow setup and switched REGISTRATION_FLOW variable to false to disable welcome screen and test manual namespace management.

When user is owning some empty namespace, or added as a contributor to such namespace, it sees no Private pipelines, as expected. But when we remove this user from contributors, so they doesn't have any namespaces, user sees all pipelines from Shared in Private section. User can successfully remove any of these "pipelines".

What did you expect to happen:
It is expected that he doesn't have access to the Dashboard at all, seeing some stub instead.
Or, if the "access without namespace" is valid scenario for work with shared entities, they are not shown in Private (namespaced) section.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]
Operations on some other entities might also be affected.

Environment:

• Kubeflow version: 1.8.0
• kfctl version: not used
• Kubernetes platform: GKE
• Kubernetes version: v1.27.10