Revert "cl refactor: add preload stage"

[xushiwei]

Reverts #893

[codecov]

Codecov Report

❌ Patch coverage is 89.56044% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.38%. Comparing base (bd9d8b1) to head (1fc039c).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
cl/compile.go	76.47%	8 Missing ⚠️
cl/ctx.go	91.86%	7 Missing ⚠️
cl/class.go	90.90%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #895      +/-   ##
==========================================
+ Coverage   88.54%   89.38%   +0.84%     
==========================================
  Files          21       20       -1     
  Lines        1946     1922      -24     
==========================================
- Hits         1723     1718       -5     
+ Misses        223      204      -19     

Flag	Coverage Δ
llgo-tests	89.38% <89.56%> (+0.84%)	⬆️

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