Support for just cleaning up dangling e2e objects

[manfredlift]

Describe the solution you'd like
[A clear and concise description of what you want to happen.]
I'd like there to be a way to just clean up dangling e2e objects.

Currently there's just option:

Flags:
      --all                     In addition to deleting Sonobuoy namespaces, also clean up dangling e2e namespaces (those with 'e2e-framework' and 'e2e-run' labels)

It'd be nice to be able to retain Sonobuoy namespace and just delete the dangling e2e objects.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Sonobuoy version:
• Kubernetes version: (use kubectl version):
• Kubernetes installer & version:
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):

[stale]

There has not been much activity here. We'll be closing this issue if there are no follow-ups within 15 days.