Fix a flaky async payment triggerer test

[remyers]

Sometimes the PeerReadyNotifier for node A has not been killed before node A connects. This causes an extra GetPeerInfo message to be sent to the switchboard and the assert(request3.remoteNodeId == remoteNodeId2) check to fail when the GetPeerInfo for node A comes before the one for node B. Just waiting to receive the AsyncPaymentTimeout message does not guarantee the notifier has been stopped.

If node A connects after node B then this race does not occur.

In the logs the error looked like this:

watch two nodes, one connects and the other times out *** FAILED ***
 02aaaa00ce2f18a967dc4f25f414e671ba6585f8ef0b8c5fb812c21064f55a2eaa did not equal 02bbbb671d15145722fb8c28d732cddb249bcc6652ed2b297ff1f77a18371b1e63 (AsyncPaymentTriggererSpec.scala:185)
 Analysis:
 Crypto$PublicKey(pub: 02aaaa00ce2f18a967dc4f25f414e671ba6585f8ef0b8c5fb812c21064f55a2eaa -> 02bbbb671d15145722fb8c28d732cddb249bcc6652ed2b297ff1f77a18371b1e63, value: ByteVector$Chunk(bytes: ByteVector$View(at: scodec.bits.ByteVector$AtArray@414cba29 -> scodec.bits.ByteVector$AtArray@317a0b5e)))

[codecov-commenter]

Codecov Report

Merging #2764 (8bf4761) into master (9ca9227) will increase coverage by 0.03%.
Report is 1 commits behind head on master.
The diff coverage is 100.00%.

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@@            Coverage Diff             @@
##           master    #2764      +/-   ##
==========================================
+ Coverage   85.84%   85.87%   +0.03%     
==========================================
  Files         216      216              
  Lines       18102    18093       -9     
  Branches      762      755       -7     
==========================================
- Hits        15540    15538       -2     
+ Misses       2562     2555       -7     

Files	Coverage Δ
...re/src/main/scala/fr/acinq/eclair/NodeParams.scala	93.39% <100.00%> (-0.03%)	⬇️
...n/scala/fr/acinq/eclair/io/PeerReadyNotifier.scala	69.23% <100.00%> (ø)
...cinq/eclair/remote/EclairInternalsSerializer.scala	97.82% <100.00%> (ø)
...scala/fr/acinq/eclair/router/BalanceEstimate.scala	98.93% <100.00%> (ø)
.../src/main/scala/fr/acinq/eclair/router/Graph.scala	97.25% <100.00%> (-0.09%)	⬇️
...cala/fr/acinq/eclair/router/RouteCalculation.scala	94.56% <100.00%> (ø)
...src/main/scala/fr/acinq/eclair/router/Router.scala	94.78% <100.00%> (ø)
...main/scala/fr/acinq/eclair/router/Validation.scala	95.00% <100.00%> (ø)

... and 7 files with indirect coverage changes