Cleanup the seeder list

Summary: This diff removes the bitcoinforks seeders which are down and add mines.

Test Plan:

drill seeder.fabien.cash

# just started, might not give results yet
drill testnet-seeder.fabien.cash

Reviewers: #bitcoin_abc, majcosta, Mengerian, jasonbcox

Reviewed By: #bitcoin_abc, majcosta, Mengerian, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D9335