cleanup sv2-proxy example

[plebhash]

similar to #1403

after a quick investivation, this example directory has no clear purpose for existing

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 19.08%. Comparing base (05fa3fc) to head (c605e0d).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1406   +/-   ##
=======================================
  Coverage   19.08%   19.08%           
=======================================
  Files         166      166           
  Lines       11066    11066           
=======================================
  Hits         2112     2112           
  Misses       8954     8954           

Flag	Coverage Δ
binary_codec_sv2-coverage	0.00% <ø> (ø)
binary_serde_sv2-coverage	3.55% <ø> (ø)
binary_sv2-coverage	5.34% <ø> (ø)
bip32_derivation-coverage	0.00% <ø> (ø)
buffer_sv2-coverage	25.02% <ø> (ø)
codec_sv2-coverage	0.01% <ø> (ø)
common_messages_sv2-coverage	0.13% <ø> (ø)
const_sv2-coverage	0.00% <ø> (ø)
error_handling-coverage	0.00% <ø> (ø)
framing_sv2-coverage	0.28% <ø> (ø)
jd_client-coverage	0.00% <ø> (ø)
jd_server-coverage	7.79% <ø> (ø)
job_declaration_sv2-coverage	0.00% <ø> (ø)
key-utils-coverage	2.39% <ø> (ø)
mining-coverage	2.43% <ø> (-0.02%)	⬇️
mining_device-coverage	0.00% <ø> (ø)
mining_proxy_sv2-coverage	0.70% <ø> (ø)
noise_sv2-coverage	4.44% <ø> (ø)
pool_sv2-coverage	2.04% <ø> (ø)
protocols	24.57% <ø> (ø)
roles	6.54% <ø> (ø)
roles_logic_sv2-coverage	7.93% <ø> (ø)
sv2_ffi-coverage	0.00% <ø> (ø)
template_distribution_sv2-coverage	0.00% <ø> (ø)
translator_sv2-coverage	9.60% <ø> (ø)
utils	?
v1-coverage	2.41% <ø> (ø)

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