net: Hardcoded seeds update for 0.21

Stats:

```
  IPv4   IPv6  Onion Pass
426728  59523   7900 Initial
426728  59523   7900 Skip entries with invalid address
426728  59523   7900 After removing duplicates
426727  59523   7900 Skip entries from suspicious hosts
123226  51785   7787 Enforce minimal number of blocks
121710  51322   7586 Require service bit 1
  4706   1427   3749 Require minimum uptime
  4124   1098   3681 Require a known and recent user agent
  4033   1075   3681 Filter out hosts with multiple bitcoin ports
   512    140    512 Look up ASNs and limit results per ASN and per net
```

Author: laanwj