update bin/test scripts to prevent double runs.

The test runner was updated to make use of autorun. This caused the
`bin/test` scripts to run Minitest twice.

actionmailer/bin/test

@@ -2,5 +2,3 @@
 
 COMPONENT_ROOT = File.expand_path("..", __dir__)
 require File.expand_path("../tools/test", COMPONENT_ROOT)
-
-exit Minitest.run(ARGV)

actionpack/bin/test

@@ -2,5 +2,3 @@
 
 COMPONENT_ROOT = File.expand_path("..", __dir__)
 require File.expand_path("../tools/test", COMPONENT_ROOT)
-
-exit Minitest.run(ARGV)

actionview/bin/test

@@ -2,5 +2,3 @@
 
 COMPONENT_ROOT = File.expand_path("..", __dir__)
 require File.expand_path("../tools/test", COMPONENT_ROOT)
-
-exit Minitest.run(ARGV)

activemodel/bin/test

@@ -2,5 +2,3 @@
 
 COMPONENT_ROOT = File.expand_path("..", __dir__)
 require File.expand_path("../tools/test", COMPONENT_ROOT)
-
-exit Minitest.run(ARGV)

activerecord/bin/test

@@ -17,5 +17,3 @@ module Minitest
 end
 
 Minitest.extensions.unshift "active_record"
-
-exit Minitest.run(ARGV)

activesupport/bin/test

@@ -2,5 +2,3 @@
 
 COMPONENT_ROOT = File.expand_path("..", __dir__)
 require File.expand_path("../tools/test", COMPONENT_ROOT)
-
-exit Minitest.run(ARGV)

tools/test.rb

@@ -13,3 +13,5 @@ def self.root
 end
 
 Rails::TestUnitReporter.executable = "bin/test"
+Minitest.run_via[:rails] = true
+require "active_support/testing/autorun"