fix: incorrect bitcoin outbound height

[ws4charlie]

Description

During Bitcoin withdraw tests in Athens3, I noticed an old issue that existed since v1. Looking at this mainnet bitcoin outbound cctx:
https://zetachain.blockpi.network/lcd/v1/public/zeta-chain/crosschain/cctx/8332/200

The cctx's outbound parameter contains a wrong "outbound_tx_observed_external_height": "578", the correct height should be 835053 in bitcoin explorer

It is a minor issue that could impact explorer, nothing about security.

Closes:

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Include instructions and any relevant details so others can reproduce.

• Tested CCTX in localnet
• Tested in development environment
• Go unit tests
• Go integration tests
• Tested via GitHub Actions

Checklist:

• I have added unit tests that prove my fix feature works

[github-actions]

!!!WARNING!!!
nosec detected in the following files: zetaclient/chains/bitcoin/observer/outbound.go

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 67.99%. Comparing base (1302dcc) to head (31a6fc7).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2243      +/-   ##
===========================================
- Coverage    68.06%   67.99%   -0.07%     
===========================================
  Files          259      259              
  Lines        16014    16030      +16     
===========================================
  Hits         10900    10900              
- Misses        4653     4669      +16     
  Partials       461      461              

Files	Coverage Δ
zetaclient/chains/bitcoin/observer/outbound.go	35.84% <0.00%> (-0.67%)	⬇️
zetaclient/chains/bitcoin/observer/observer.go	14.31% <0.00%> (-0.31%)	⬇️