Update the ActiveRecord tests to not set unused options

This makes a test fail, but it is revealing a bug in Arel master.

activerecord/lib/active_record/test_case.rb

@@ -36,21 +36,6 @@ module ActiveRecord
       assert_queries(0, &block)
     end
 
-    def self.use_concurrent_connections
-      setup :connection_allow_concurrency_setup
-      teardown :connection_allow_concurrency_teardown
-    end
-
-    def connection_allow_concurrency_setup
-      @connection = ActiveRecord::Base.remove_connection
-      ActiveRecord::Base.establish_connection(@connection.merge({:allow_concurrency => true}))
-    end
-
-    def connection_allow_concurrency_teardown
-      ActiveRecord::Base.clear_all_connections!
-      ActiveRecord::Base.establish_connection(@connection)
-    end
-
     def with_kcode(kcode)
       if RUBY_VERSION < '1.9'
         orig_kcode, $KCODE = $KCODE, kcode

activerecord/test/cases/locking_test.rb

@@ -306,8 +306,6 @@ unless current_adapter?(:SybaseAdapter, :OpenBaseAdapter)
     end
 
     if current_adapter?(:PostgreSQLAdapter, :OracleAdapter)
-      use_concurrent_connections
-
       def test_no_locks_no_wait
         first, second = duel { Person.find 1 }
         assert first.end > second.end

activerecord/test/cases/transactions_test.rb

@@ -529,8 +529,6 @@ end if Topic.connection.supports_savepoints?
 
 if current_adapter?(:PostgreSQLAdapter)
   class ConcurrentTransactionTest < TransactionTest
-    use_concurrent_connections
-
     # This will cause transactions to overlap and fail unless they are performed on
     # separate database connections.
     def test_transaction_per_thread