Replace deprecated tempest decorators

The function 'tempest.test.attr()' has been moved in Pike to
'tempest.lib.decorators.attr()' and will be removed in a future
version[1]. This patch replaces 'tempest.test.attr()' with
'tempest.lib.decorators.attr().'

[1] Iaafbb112b6eee458089cc49918359a8a8d0485e2

Change-Id: I2598c6ad24fe4df172db56b79f4aaa4a96a2d23e

contrib/tempest/tempest/scenario/test_host_reservation.py

@@ -18,9 +18,9 @@ import time
 from oslo_log import log as logging
 from tempest.common import waiters
 from tempest import config
+from tempest.lib import decorators
 from tempest.lib import exceptions
 from tempest.scenario import resource_reservation_scenario as rrs
-from tempest import test
 
 CONF = config.CONF
 
@@ -78,7 +78,7 @@ class TestHostReservationScenario(rrs.ResourceReservationScenarioTest):
             raise exceptions.NotFound(err_msg)
         return aggr
 
-    @test.attr(type='smoke')
+    @decorators.attr(type='smoke')
     def test_host_reservation(self):
 
         def wait_until_aggregated(aggregate_name, host_name):

contrib/tempest/tempest/scenario/test_instance_reservation.py

@@ -140,7 +140,7 @@ class TestInstanceReservationScenario(rrs.ResourceReservationScenarioTest):
     # TODO(cmart): add blazar to services after pushing this code into tempest
     @decorators.skip_because('Instance reservation is not supported yet.',
                              bug='1659200')
-    @test.attr(type='slow')
+    @decorators.attr(type='slow')
     @test.services('compute', 'network')
     def test_server_basic_resource_reservation_operation(self):
         start_date = datetime.datetime.utcnow() + datetime.timedelta(minutes=1)