Merge bitcoin/bitcoin#22060: contrib: add torv3 seed nodes for testnet, drop v2 ones

6fe0516858 contrib: add torv3 seed nodes for testnet, drop v2 ones (Jon Atack)

Pull request description:

  Replace the ancient (2015) Tor V2 hardcoded seeds with new Tor V3 ones. This needs to be done before 0.22 to make sure onion-only testnet nodes can still connect to the network. Continues #21560.

  Ways to test:
  - Re-generate ` src/chainparamsseeds.h` with `cd contrib/seeds && python3 generate-seeds.py . > ../../src/chainparamsseeds.h`, check if git tree stays the same.
  - Create a new testnet node with `bitcoind -testnet -onlynet=onion -proxy=127.0.0.1:9050` (or delete `~/.bitcoin/testnet3/peers.dat`), check if it is able to connect to the network and get blocks.
  - Check if the addresses are connectable for ex.:
  ```python3
  #!/usr/bin/env python3
  import subprocess
  with open('contrib/seeds/nodes_test.txt') as f:
      for line in (line for line in (line.rstrip().split('#', 1)[0] for line in f) if line):
          subprocess.call(["nc", "-v", "-x", "127.0.0.1:9050", "-z"] + line.split(':'))
  ```

  Thanks to jonatack for providing the list.

ACKs for top commit:
  jonatack:
    ACK 6fe0516858

Tree-SHA512: 61bfdb44dfab9d02b75e5cb06c089a3b1a1fe7134875e1d09166c4116e961d809aa25422fe03f068876e9423b571ecc4a0c7a7eeacba4aac3b2768717f3ee6d6

contrib/seeds/nodes_test.txt

@@ -1,11 +1,16 @@
 # List of fixed seed nodes for testnet
 
 # Onion nodes
-thfsmmn2jbitcoin.onion:18333
-it2pj4f7657g3rhi.onion:18333
-nkf5e6b7pl4jfd4a.onion:18333
-4zhkir2ofl7orfom.onion:18333
-t6xj6wilh4ytvcs7.onion:18333
-i6y6ivorwakd7nw3.onion:18333
-ubqj4rsu3nqtxmtp.onion:18333
+35k2va6vyw4oo5ly2quvcszgdqr56kcnfgcqpnpcffut4jn3mhhwgbid.onion:18333
+blo2esfvk2rr7sr4jspmu3vt2vpgr5rigflsj645fnku7v4qmljurtid.onion:18333
+fuckcswupr5rmlvx2kqqrrosxvjyong4hatmuvxsvtcwe4dsh5rus7qd.onion:18333
+gblylyacjlitd2ywdmo2qqylwtdky7kgeqfvlhiw4zdag4x62tx54hyd.onion:18333
+gzwpduv33l7yze3bcdzj3inebiyjwddjnwvnjhh5wvnv4me76mjt2kad.onion:18333
+h3rphzofxzq52tb63mg5f6kc4my3fkcrgh3m5qryeatts43iljbawiid.onion:18333
+kf4qlhek34b3kgyxyodlmvgm4bxfrjsbjtgayyaiuyhr2eoyfgtm3bad.onion:18333
+mc7k47ndjvvhcgs54wmjzxvate4rtuybbjoryikdssjhcxlx27psbyqd.onion:18333
+mrhiniicugfo7mgrwv3wtolk3tptlcw2uq7ih6sq43fa4k4zbilut3yd.onion:18333
+uiudyws3qizgmepfoh7wwjmsoxoxut4qrmotjjhrn247xnjopr7sfcid.onion:18333
+zc2wvoqcezcrf64trji6jmhtss34a5ds5ntzdhqegzvex3ynrd7nxcad.onion:18333
+zd5m3dgdn46naj36pxvvcalfw2paecle6sdxq64ptwxtxjomkywpklqd.onion:18333