Consistently pass DefaultRouter::new Default scoring parameters

[TheBlueMatt]

In 26c1639 (and later in 50c55dc and
fb693ec) we switched to using Default::default() to initialize () for scoring parameters in tests. One ()s slipped back in recently, which we replace here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.67%. Comparing base (f89e963) to head (841e9de).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3258      +/-   ##
==========================================
- Coverage   89.72%   89.67%   -0.05%     
==========================================
  Files         125      125              
  Lines      102801   102801              
  Branches   102801   102801              
==========================================
- Hits        92234    92190      -44     
- Misses       7859     7896      +37     
- Partials     2708     2715       +7     

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