Sunset TPO onion v2 hidden services 🌇

Onion v2 hidden services have been deprecated and are not longer supported. We should remove them from our infrastructure.

• stop onion.torproject.org from generating pointers to the v2 links (#40668 (closed))
• deconfigure v2 onions from torrc instances
• stop/retire onionbalance-01 machine
• destroy v2 onion keys
• remove all calls to onion_global_service_hostname in puppet
• remove the onion_global_service_hostname function from puppet
• remove the onion::balance class from puppet
• remove all onionv2 support from the onion class