When in IBD, we'd like to use all our outbound peers to help us
sync the chain. Disconnect any outbound peers whose headers have
insufficient work.
Github-Pull: #11490
Rebased-From: c60fd71a65e841efe187992f46c583a704cc37f5
Nodes don't consider themselves out of "initial block download" until
their active chain has more work than nMinimumChainWork.
While in initial block download, nodes won't relay blocks to their
peers, so test that this parameter functions as intended by verifying
that block relay only succeeds past a given node once its
nMinimumChainWork has been exceeded.
Github-Pull: #10357
Rebased-From: eac64bb7a3b6aba747403b23b3b1d3609843f8db
