bootstrap: initialize http proxy after user module loader setup

[joyeecheung]

The externalized undici relies on the user module loader, so in the externalized build, initialization of http proxy which relies on undici needs to be deferred until after the user module loader is initialized.

Refs: #58865

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.09%. Comparing base (8173d9d) to head (1d07514).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #58938   +/-   ##
=======================================
  Coverage   90.09%   90.09%           
=======================================
  Files         640      640           
  Lines      188462   188476   +14     
  Branches    36962    36966    +4     
=======================================
+ Hits       169786   169808   +22     
+ Misses      11404    11385   -19     
- Partials     7272     7283   +11     

Files with missing lines	Coverage Δ
lib/internal/process/pre_execution.js	90.74% <100.00%> (-0.65%)	⬇️

... and 35 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/67799/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/67807/