Update the seeder list

Summary: This remove the seeders that are no longer maintained and/or on the wrong chain from our list. A new mainnet seeder has been added to counterbalance this.

Test Plan:

Run mainnet and testnet IBD.

Check the new seeder is working:

drill seeder2.fabien.cash

should return a list of ip addresses

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Differential Revision: https://reviews.bitcoinabc.org/D11643