test: Allow setting a HTTP proxy using an env variable for the integretaion tests

[poljar]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.50%. Comparing base (183116a) to head (bd789e3).
⚠️ Report is 20 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5948      +/-   ##
==========================================
- Coverage   88.50%   88.50%   -0.01%     
==========================================
  Files         362      362              
  Lines      103373   103373              
  Branches   103373   103373              
==========================================
- Hits        91491    91487       -4     
- Misses       7537     7539       +2     
- Partials     4345     4347       +2     

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[codspeed-hq]

CodSpeed Performance Report

Merging #5948 will not alter performance

_{Comparing poljar/proxy-env-variable (bd789e3) with main (2522a36)}

Summary

✅ 50 untouched

[zecakeh]

Don't the default environment variables supported by reqwest work out of the box: https://docs.rs/reqwest/latest/reqwest/#proxies?

[poljar]

Don't the default environment variables supported by reqwest work out of the box: https://docs.rs/reqwest/latest/reqwest/#proxies?

Oh, duh. Indeed they do.