```
Before PR: If peers.dat is empty and -dnsseed=0, bitcoind will fallback on to fixed seeds but only after a 60 seconds delay.
After PR: There's no 60 second delay.
To reproduce:
rm ~/.bitcoin/peers.dat && src/bitcoind -dnsseed=0 without and with patch code
Other changes in the PR:
-fixedseeds command line argument added: -dnsseed=0 -fixedseeds=0 -addnode=X provides a trusted peer only setup. -dnsseed=0 -fixedseeds=0 allows for a addnode RPC to add a trusted peer without falling back to hardcoded seeds.
```
Note to reviewers: the test feature_config_args.py now takes forever to run, this will be fixed in a follow-up.
Backport of core#19884.
Depends on D10907.
Ref T1696.