Avoid checking fallback candidates' DirPorts if they are down in OnionOO
Exclude relays that have been down for 1 or more days from the fallback candidate list.
When a relay operator has multiple relays, this prioritises relays that are up over relays that are down.
I'll roll this into the #18828 (moved) branch.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information