ERL: Use IP address instead of IP:port pair

[algorandskiy]

Summary

Make ERL more strict by distinguishing IP addresses instead of connections.

Test Plan

Cluster performance test results

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.

Project coverage is 51.88%. Comparing base (db7f162) to head (3991111).

Files with missing lines	Patch %	Lines
util/rateLimit.go	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6176      +/-   ##
==========================================
+ Coverage   51.86%   51.88%   +0.02%     
==========================================
  Files         639      639              
  Lines       85492    85494       +2     
==========================================
+ Hits        44338    44358      +20     
+ Misses      38339    38322      -17     
+ Partials     2815     2814       -1     

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[cce]

Let's say you have N conns per IP, ERL sets up the closeReservation(wsPeer) is called by the wsPeer's OnClose() handler for each of N conns (not per IP) so you will end up calling delete multiple times for each conn (not per IP) and also, the capacity that is reserved for this IP (CapacityPerReservation) will be returned N times

[cce]

actually, since N conns are sharing one erl.capacityByClient[IP] entry, ERL will only call wsPeer.OnClose() when it sees the IP missing from the map. So that means if the first conn goes away, it will return the CapacityPerReservation back and delete itself from the map, even though the other conns are still running.

I think there needs to be an implementation of the ErlClient interface, like a meta-client, that manages setting OnClose() handlers for all the wsPeers sharing the same IP, something like that, and function that takes a wsPeer and looks it up by IP, and returns a IPBasedERLClient impl to pass to ConsumeCapacity(c ErlClient). Then when the IPBasedErlClient notices all the child wsPeers have called OnClose, it calls its own OnClose, which in turns calls ERL.closeReservation()