TrivialFix: Do not use synchronous_reader argument
TrivialFix: Do not use synchronous_reader argument

While running the following was observed in the captured stderr:

neutron/tests/unit/testlib_api.py:104: DeprecationWarning: Using the
'synchronous_reader' argument is deprecated: argument value is
propagated from the parent _TransactionFactory
      synchronous_reader=True)

I simply removed the argument.

The parent ref is here and defaults to True:
https://github.com/openstack/oslo.db/blob/master/oslo_db/sqlalchemy/enginefacade.py#L160

TrivialFix

Change-Id: Ic1744d97edb69b0f806aea7f2cde0b89b6bfbce1

openstack/neutron,openstack/neutron,eayunstack/neutron,eayunstack/neutron,openstack/neutron,huntxu/neutron,mahak/neutron,huntxu/neutron,mahak/neutron,noironetworks/neutron,noironetworks/neutron,mahak/neutron