Update Washington state flex speed test

[leonardehrenfried]

Summary

The Washington state flex speed tests started showing very strange results a couple of months ago.

This is probably because the flex spec changed and lots of feeds became invalid. They also didn't differentiate between flex+transit and flex direct.

For this reason I decided to start afresh.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.92%. Comparing base (440498f) to head (786805a).
Report is 18 commits behind head on dev-2.x.

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #6175      +/-   ##
=============================================
- Coverage      69.93%   69.92%   -0.01%     
+ Complexity     17730    17725       -5     
=============================================
  Files           1996     1996              
  Lines          75402    75402              
  Branches        7717     7717              
=============================================
- Hits           52731    52725       -6     
- Misses         19995    19998       +3     
- Partials        2676     2679       +3     

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