tests: don't override base object test class attributes
tests: don't override base object test class attributes

DNSNameServerDbObjectTestCase was overriding self.db_objs and
self.obj_fields if the attributes did not have unique order/address
fields generated by get_random_fields. But since
Id1ca4ce7b134d9729e68661cedb2f5556e58d6ff landed, we should have also
updated self.objs, otherwise test_filtering_by_fields will fail later
when it will try to find an object with attributes that were not used
when creating the object targeted by the filtering attempt.

Instead of adding the update for self.objs in the
DNSNameServerDbObjectTestCase test class, I went with an alternative
approach, getting rid of overriding logic completely. The rationale for
the path is that there is nothing wrong in duplicate address and order
field values (at least as per underlying model definition), and hence
our tests should be resilient against that kind of scenario.

So instead of comparing all fields for an object, just make sure that
the order monotonically goes up/down in the sorted result, and ignore
other fields to be strictly ordered.

Change-Id: Ic956072de5dab336f83b04bddfa9da967b2865b2
Closes-Bug: #1623425

openstack/neutron,openstack/neutron,noironetworks/neutron,cloudbase/neutron,mahak/neutron,sebrandon1/neutron,cloudbase/neutron,eayunstack/neutron,mahak/neutron,openstack/neutron,huntxu/neutron,eayunstack/neutron,mahak/neutron,noironetworks/neutron,sebrandon1/neutron,huntxu/neutron