Add GKE router to nfr workflow

[bjee19]

Add a small fix to the nfr workflow which involves creating a GKE router.

Passing nfr workflow action: https://github.com/nginx/nginx-gateway-fabric/actions/runs/15143764098

PR containing nfr workflow test results is here: #3391

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.79%. Comparing base (a8d373e) to head (f3c93e8).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3392      +/-   ##
==========================================
+ Coverage   86.77%   86.79%   +0.02%     
==========================================
  Files         129      129              
  Lines       14862    14862              
  Branches       62       62              
==========================================
+ Hits        12897    12900       +3     
+ Misses       1817     1815       -2     
+ Partials      148      147       -1     

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