tests: Remove unused "test_airport" fixture
tests: Remove unused "test_airport" fixture

skylines-project/skylines,Turbo87/skylines,skylines-project/skylines,shadowoneau/skylines,shadowoneau/skylines,shadowoneau/skylines,Turbo87/skylines,RBE-Avionik/skylines,Turbo87/skylines,Harry-R/skylines,Harry-R/skylines,Harry-R/skylines,RBE-Avionik/skylines,shadowoneau/skylines,skylines-project/skylines,RBE-Avionik/skylines,RBE-Avionik/skylines,Harry-R/skylines,skylines-project/skylines,Turbo87/skylines