Update seeds

Summary: See title.

Test Plan:
Script from D3809:

T=$(cat nodes_main.txt | wc -l); N=$(./test-seeds.sh < nodes_main.txt | wc -l); echo "scale=3; $N / $T" | bc
84% of mainnet seed nodes successfully connected on my machine

T=$(cat nodes_test.txt | wc -l); N=$(./test-seeds.sh --testnet < nodes_test.txt | wc -l); echo "scale=3; $N / $T" | bc
81% of testnet seed nodes successfully connected on my machine

Reviewers: #bitcoin_abc, deadalnix, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D3883