transaction sync: Transition test

[brianolson]

Summary

Test for a network in transition.
Runs a 6 node network with the following topology:

New Leaf 1                           New Leaf 2
           > New Relay - Old Relay <
Old Leaf 1                           Old Leaf 2

"New" and "Old" can mean different algod/goal/kmd binary versions.
It can also or separately mean config.json updates. (set --old-bin
and --new-bin to the same dir, set --new-config or --old-config to
overlay json onto the net temlplate generated config.json of new or
old nodes.

In the test each leaf submits a simple payment transaction from its
unlocked wallet to a dummy account '\x00...\x0N'. A few rounds are
waited then each leaf verifies that it can see all the expected
account values.

The test then waits 100 rounds and checks that the 4 leaves are each
a block proposer a reasonable fraction of the 100 rounds.

Test Plan

master vs txnsync

python3 test/scripts/transition_mix_test.py --old-branch origin/master --new-branch origin/feature/txnsync

txnsync vs txnsync-protocol-2.1

python3 test/scripts/transition_mix_test.py --old-branch origin/feature/txnsync --new-branch origin/feature/txnsync --old-config='{"NetworkProtocolVersion":"2.1"}'

[codecov-commenter]

Codecov Report

Merging #3882 (1357455) into master (9d9d759) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3882   +/-   ##
=======================================
  Coverage   49.97%   49.98%           
=======================================
  Files         393      393           
  Lines       68390    68390           
=======================================
+ Hits        34181    34186    +5     
+ Misses      30473    30469    -4     
+ Partials     3736     3735    -1     

Impacted Files	Coverage Δ
ledger/roundlru.go	90.56% <0.00%> (-5.67%)	⬇️
cmd/algoh/blockWatcher.go	77.77% <0.00%> (-3.18%)	⬇️
cmd/tealdbg/debugger.go	71.42% <0.00%> (-0.99%)	⬇️
network/wsNetwork.go	62.79% <0.00%> (ø)
data/transactions/verify/txn.go	45.02% <0.00%> (+0.86%)	⬆️
network/wsPeer.go	68.61% <0.00%> (+2.77%)	⬆️

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