fix cross chain hub e2e test

[doitian]

Remove steps 16~18, which closes the ln channel.

Reasons to remove these steps:

1. The channel is opened in setup-lnd.sh. If we do need to test this,
   we should also open the lightning channel in bruno.
2. It is not our concern that lnd can successfully close a channel.
3. The implementation have bugs and fixing them is time consuming.
   1. Closing a channel is async in lnd, and we should block the test until
      the response stream closes, otherwise it is not to assert that we
      have closed the channel successfully.
   2. Closing a channel in lnd requires generating btc blocks so we
      need to call bitcoind rpc as well.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.64%. Comparing base (e7109ca) to head (0a442b1).
Report is 18 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #275      +/-   ##
==========================================
+ Coverage   45.10%   50.64%   +5.54%     
==========================================
  Files          44       44              
  Lines       27460    32425    +4965     
==========================================
+ Hits        12385    16423    +4038     
- Misses      15075    16002     +927     

Flag	Coverage Δ
unittests	50.64% <ø> (+5.54%)	⬆️

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