Fix flaky transmission_interface tests by making them deterministic.

[sgmurray]

Fixes #1555

The transmission_interface tests would give non deterministic spurious failures. The non determinism was because tests were randomly generated using the system time to seed the random number generator. The spurious failures were due to occasionally occurring tiny rounding errors from floating point math.

By seeding the random number generator the tests become deterministic and we avoid the spurious failures.
Additionally, changing the order of some of the multiplications seems to reduce the rounding error.

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[christophfroehlich]

Thanks for picking this up!

Please fix the pre-commit errors (you can install it locally and run the tests before you push).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.07%. Comparing base (a1ad523) to head (457d2f0).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1665   +/-   ##
=======================================
  Coverage   88.07%   88.07%           
=======================================
  Files         108      108           
  Lines       10023    10024    +1     
  Branches      892      892           
=======================================
+ Hits         8828     8829    +1     
  Misses        876      876           
  Partials      319      319           

Flag	Coverage Δ
unittests	88.07% <100.00%> (+<0.01%)	⬆️

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

Files	Coverage Δ
...ission_interface/four_bar_linkage_transmission.hpp	77.89% <100.00%> (ø)
...smission_interface/test/random_generator_utils.hpp	100.00% <100.00%> (ø)

[bmagyar]

thank you!