Switch to use idempotent_id decorator from tempest.lib

Decorator idempotent_id() in tempest.test is deprecated and
tempest.lib.decorators.idempotent_id() should be used instead.
This patch switch all tempest tests to use new decorator.

Change-Id: I2df9c13fbb44b8807da6805761ad30bfd010dc55
diff --git a/neutron/tests/tempest/api/test_extensions.py b/neutron/tests/tempest/api/test_extensions.py
index b1b09e8..3809a93 100644
--- a/neutron/tests/tempest/api/test_extensions.py
+++ b/neutron/tests/tempest/api/test_extensions.py
@@ -10,6 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from tempest.lib import decorators
 from tempest import test
 
 from neutron.tests.tempest.api import base
@@ -27,14 +28,14 @@
         else:
             self.assertNotIn(ext, extensions)
 
-    @test.idempotent_id('262420b7-a4bb-4a3e-b4b5-e73bad18df8c')
+    @decorators.idempotent_id('262420b7-a4bb-4a3e-b4b5-e73bad18df8c')
     def test_list_extensions_sorting(self):
         self._test_list_extensions_includes('sorting')
 
-    @test.idempotent_id('19db409e-a23f-445d-8bc8-ca3d64c84706')
+    @decorators.idempotent_id('19db409e-a23f-445d-8bc8-ca3d64c84706')
     def test_list_extensions_pagination(self):
         self._test_list_extensions_includes('pagination')
 
-    @test.idempotent_id('155b7bc2-e358-4dd8-bf3e-1774c084567f')
+    @decorators.idempotent_id('155b7bc2-e358-4dd8-bf3e-1774c084567f')
     def test_list_extensions_project_id(self):
         self._test_list_extensions_includes('project-id')