Simplify reduce_wheel_speed_until_steering_reached logic (backport #2396)

[mergify]

Description

While checking #2392 I was confused by the code. I used the chance to simplify the logic a bit.

Is this user-facing behavior change?

Minimal, the scale is continuous now as cos(max_phi_delta) / cos(min_phi_delta) is not exactly 0.01.

Did you use Generative AI?

no

Additional Information

---

This is an automatic backport of pull request #2396 done by [Mergify](https://mergify.com).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.44%. Comparing base (96b399d) to head (b33c432).

Additional details and impacted files

@@            Coverage Diff             @@
##           humble    #2426      +/-   ##
==========================================
- Coverage   69.45%   69.44%   -0.01%     
==========================================
  Files         128      128              
  Lines       14580    14579       -1     
  Branches     9174     9170       -4     
==========================================
- Hits        10126    10125       -1     
  Misses       1185     1185              
  Partials     3269     3269              

Flag	Coverage Δ
unittests	69.44% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ring_controllers_library/src/steering_odometry.cpp	81.92% <100.00%> (-0.11%)	⬇️

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