Reducing those iterations results in a buggy compiler that causes
nimbus_beacon_node to fail at runtime with:
"FAT 2021-01-09 21:19:52.417+01:00 Could not obtain PeerID from network key topics="networking" tid=26805 file=eth2_network.nim:1393"
* log when database is loading (to avoid confusion)
* generate network keys later during startup
* fix quarantine not scheduling chain of parents for download and
increase size to one epoch
* log validator count, enr and peerid more clearly on startup
Zahary Karadjov
Ștefan Talpalaru
Jacek Sieka