Remove `channelReserve.getOrElse(0 sat)`

[pm47]

With the requirements added by #2430, we can get rid of the superfluous degrees of freedom around channel reserve, while still leaving the model untouched.

This revealed some inconsistencies in test data.

[codecov-commenter]

Codecov Report

Merging #2432 (6a4e972) into master (b00a0b2) will increase coverage by 0.03%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2432      +/-   ##
==========================================
+ Coverage   84.76%   84.79%   +0.03%     
==========================================
  Files         198      198              
  Lines       15735    15734       -1     
  Branches      654      665      +11     
==========================================
+ Hits        13337    13341       +4     
+ Misses       2398     2393       -5     

Impacted Files	Coverage Δ
...in/scala/fr/acinq/eclair/channel/Commitments.scala	94.87% <100.00%> (-0.02%)	:arrow_down:
...c/main/scala/fr/acinq/eclair/channel/Helpers.scala	95.03% <100.00%> (ø)
...q/eclair/channel/fsm/ChannelOpenSingleFunded.scala	94.19% <100.00%> (ø)
...main/scala/fr/acinq/eclair/router/Validation.scala	94.11% <0.00%> (-1.31%)	:arrow_down:
...main/scala/fr/acinq/eclair/io/PeerConnection.scala	86.02% <0.00%> (-0.37%)	:arrow_down:
...fr/acinq/eclair/channel/InteractiveTxBuilder.scala	85.60% <0.00%> (+1.04%)	:arrow_up:
.../acinq/eclair/blockchain/bitcoind/ZmqWatcher.scala	88.13% <0.00%> (+2.54%)	:arrow_up:
...clair/blockchain/bitcoind/rpc/BatchingClient.scala	100.00% <0.00%> (+13.63%)	:arrow_up: