remove skip for test_connectivity_between_vms_on_different_networks

test test_connectivity_between_vms_on_different_networks was skipped due
to bug https://bugs.launchpad.net/tempest/+bug/1610994 which seems no
longer valid. I run the test on a valid environment and its passing.

Change-Id: I8c607758cb98978c0cda92b2b14467a1a972d33b
diff --git a/tempest/scenario/test_network_basic_ops.py b/tempest/scenario/test_network_basic_ops.py
index bcd4ddb..8212e75 100644
--- a/tempest/scenario/test_network_basic_ops.py
+++ b/tempest/scenario/test_network_basic_ops.py
@@ -435,7 +435,6 @@
     @testtools.skipIf(CONF.network.shared_physical_network,
                       'Connectivity can only be tested when in a '
                       'multitenant network environment')
-    @decorators.skip_because(bug="1610994")
     @decorators.attr(type='slow')
     @utils.services('compute', 'network')
     def test_connectivity_between_vms_on_different_networks(self):