Merge pull request rails#50161 from fatkodima/remove-duplicate-line

Remove duplicate  assignment from ActiveRecord's Rakefile

Author: jonathanhefner

activerecord/Rakefile

@@ -66,8 +66,6 @@ end
       } + FileList["test/cases/adapters/#{adapter_short}/**/*_test.rb"])
       files = files + FileList["test/cases/adapters/abstract_mysql_adapter/**/*_test.rb"] if ["mysql2", "trilogy"].include?(adapter)
 
-      t.test_files = files
-
       t.test_files = files
       t.warning = true
       t.verbose = true