Don't allow duplicate P2P connections from the same IP by default

[peterjgilbert]

No description provided.

[codecov]

Codecov Report

Merging #2558 into master will increase coverage by 0.13%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2558      +/-   ##
==========================================
+ Coverage   67.34%   67.48%   +0.13%     
==========================================
  Files         330      330              
  Lines       30564    30566       +2     
==========================================
+ Hits        20582    20626      +44     
+ Misses       7447     7413      -34     
+ Partials     2535     2527       -8

Impacted Files	Coverage Δ
go/consensus/tendermint/tendermint.go	66.18% <100%> (+1.53%)	⬆️
go/worker/keymanager/service.go	55.55% <0%> (-22.23%)	⬇️
go/worker/common/host/interface.go	53.84% <0%> (-15.39%)	⬇️
...consensus/tendermint/apps/roothash/transactions.go	51.13% <0%> (-6.82%)	⬇️
go/worker/keymanager/worker.go	59.45% <0%> (-3.61%)	⬇️
go/runtime/tagindexer/tagindexer.go	68.96% <0%> (-2.3%)	⬇️
go/roothash/api/commitment/pool.go	68.43% <0%> (-2.07%)	⬇️
go/storage/mkvs/urkel/iterator.go	83.76% <0%> (-1.3%)	⬇️
go/runtime/transaction/transaction.go	78.04% <0%> (-1.22%)	⬇️
go/worker/merge/committee/node.go	75.9% <0%> (-0.25%)	⬇️
... and 15 more

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[Yawning]

Edit: I'm dumb and sleep deprived.

This won't fix the root cause, and it's still possible to do horrible things to the network.