test pg, rm unused requires.

activerecord/test/cases/adapters/postgresql/array_test.rb

 # encoding: utf-8
 require "cases/helper"
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlArrayTest < ActiveRecord::TestCase
   class PgArray < ActiveRecord::Base

activerecord/test/cases/adapters/postgresql/bytea_test.rb

 # encoding: utf-8
-
 require "cases/helper"
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlByteaTest < ActiveRecord::TestCase
   class ByteaDataType < ActiveRecord::Base

activerecord/test/cases/adapters/postgresql/citext_test.rb

 # encoding: utf-8
-
 require 'cases/helper'
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 if ActiveRecord::Base.connection.supports_extensions?
   class PostgresqlCitextTest < ActiveRecord::TestCase

activerecord/test/cases/adapters/postgresql/composite_test.rb

 # -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 module PostgresqlCompositeBehavior
   include ConnectionHelper

activerecord/test/cases/adapters/postgresql/domain_test.rb

 # -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlDomainTest < ActiveRecord::TestCase
   include ConnectionHelper

activerecord/test/cases/adapters/postgresql/extension_migration_test.rb

 require "cases/helper"
-require "active_record/base"
-require "active_record/connection_adapters/postgresql_adapter"
 
 class PostgresqlExtensionMigrationTest < ActiveRecord::TestCase
   self.use_transactional_fixtures = false

activerecord/test/cases/adapters/postgresql/full_text_test.rb

 # encoding: utf-8
-
 require "cases/helper"
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlFullTextTest < ActiveRecord::TestCase
   class PostgresqlTsvector < ActiveRecord::Base; end

activerecord/test/cases/adapters/postgresql/ltree_test.rb

 # encoding: utf-8
 require "cases/helper"
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlLtreeTest < ActiveRecord::TestCase
   class Ltree < ActiveRecord::Base

activerecord/test/cases/adapters/postgresql/network_test.rb

 # encoding: utf-8
-
 require "cases/helper"
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlNetworkTest < ActiveRecord::TestCase
   class PostgresqlNetworkAddress < ActiveRecord::Base

activerecord/test/cases/adapters/postgresql/range_test.rb

 require "cases/helper"
 require 'support/connection_helper'
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 if ActiveRecord::Base.connection.supports_ranges?
   class PostgresqlRange < ActiveRecord::Base

activerecord/test/cases/adapters/postgresql/xml_test.rb

 # encoding: utf-8
-
 require 'cases/helper'
-require 'active_record/base'
-require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlXMLTest < ActiveRecord::TestCase
   class XmlDataType < ActiveRecord::Base