Fix HaProxy fallback server and others fixes

[olethanh]

Resolve a few issue I encountered when doing the mass deployment of 1.7.1

1. Fix the Fallback server in haproxy getting removed and rending it unresponsive
2. Fix CPU detection on coco-1
3. Update doc on how to setup the dev env
4. Speed up free port detection for forwarding, making allocate and restart faster.
5. Add a debug endpint for haproxy
6. Log error that get caugh by the json_error_middleware

[codecov]

Codecov Report

Attention: Patch coverage is 73.62637% with 24 lines in your changes missing coverage. Please review.

Project coverage is 64.76%. Comparing base (91891de) to head (4b98190).
Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aleph/vm/orchestrator/views/__init__.py	18.18%	9 Missing ⚠️
src/aleph/vm/haproxy.py	42.85%	4 Missing ⚠️
src/aleph/vm/models.py	20.00%	4 Missing ⚠️
tests/supervisor/test_haproxy.py	93.75%	2 Missing and 2 partials ⚠️
src/aleph/vm/orchestrator/machine.py	0.00%	2 Missing ⚠️
src/aleph/vm/pool.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #822      +/-   ##
==========================================
+ Coverage   63.86%   64.76%   +0.90%     
==========================================
  Files          86       87       +1     
  Lines        7937     8021      +84     
  Branches      708      716       +8     
==========================================
+ Hits         5069     5195     +126     
+ Misses       2656     2593      -63     
- Partials      212      233      +21     

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