remove service-type from neutron extension list

service-type as an extension is only exposed if neutron advanced
services are enabled because neutron extensions are unlike nova
extensions and aren't directly loaded things, but interfaces that
plugins register that they support.

Change-Id: I6c38bace04070d71b74fa2b18866b3976f2a8524
Closes-Bug: #1491333
diff --git a/tempest/api/network/test_extensions.py b/tempest/api/network/test_extensions.py
index f56688f..d6b03eb 100644
--- a/tempest/api/network/test_extensions.py
+++ b/tempest/api/network/test_extensions.py
@@ -40,7 +40,7 @@
                           'agent', 'dhcp_agent_scheduler', 'provider',
                           'router', 'extraroute', 'external-net',
                           'allowed-address-pairs', 'extra_dhcp_opt',
-                          'metering', 'dvr', 'service-type']
+                          'metering', 'dvr']
         expected_alias = [ext for ext in expected_alias if
                           test.is_extension_enabled(ext, 'network')]
         actual_alias = list()