remove dead code from src/doubletriple

[araujoms]

More dead code removal. Some refactoring will allow even more removals, but I prefer to focus on just deleting stuff now before changing anything.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.82%. Comparing base (f00b992) to head (801389e).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #240       +/-   ##
===========================================
+ Coverage   49.26%   60.82%   +11.56%     
===========================================
  Files          63       61        -2     
  Lines        3400     2739      -661     
===========================================
- Hits         1675     1666        -9     
+ Misses       1725     1073      -652     

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