Add a landscape cleanup action

[castrojo]

@popey has been doing some great work pruning busted URLs and busted logos via scripts. We've been chatting about this at kubecon so writing it down. This is a tracking issue for taking those scripts and moving them to a github action.

• Then we can cron cleanups in the background
• We can clean up other cruft, etc.
• Reuse this across the landscape of landscapes