Add neutron_tempest_plugin.scenario to skip list

* neutron_tempest_plugin.scenario tests are not yet stable.
  In upstream CI, it is non-voting, so adding it to skip list.

Closes-Bug: #1737940
Change-Id: I9fb47520a5c74df2379695007acea77020c1af5a

roles/validate-tempest/vars/tempest_skip_master.yml

@@ -5,3 +5,9 @@ known_failures:
   - test: 'tempest.scenario.test_network_basic_ops.TestNetworkBasicOps.test_mtu_sized_frames'
     reason: 'Test is failing, it is being investigated'
     lp: 'https://bugs.launchpad.net/tripleo/+bug/1731988'
+  - test: 'neutron_tempest_plugin.scenario'
+    reason: 'Neutron Tempest plugin scenario tests are not yet stable.'
+    lp: 'https://launchpad.net/bugs/1737940'
+  - test: 'neutron_tempest_plugin.api.test_trunk_negative.TrunkTestMtusJSON.test_add_subport_with_mtu_greater_than_trunk'
+    reason: 'Promotion job fails with timeout on mtu test.'
+    lp: 'https://bugs.launchpad.net/tripleo/+bug/1737485'

roles/validate-tempest/vars/tempest_skip_ocata.yml

@@ -69,3 +69,6 @@ known_failures:
   - test: 'tempest.api.identity.admin.v3.test_roles.RolesV3TestJSON.test_implied_roles_create_check_show_delete'
     reason: 'Difference in Implied Roles check API return code'
     lp: 'https://bugs.launchpad.net/keystone/+bug/1660603'
+  - test: 'neutron.tests.tempest.scenario'
+    reason: 'Neutron tempest plugin scenario tests are unstable'
+    lp: 'https://launchpad.net/bugs/1737940'

roles/validate-tempest/vars/tempest_skip_pike.yml

@@ -63,3 +63,6 @@ known_failures:
   - test: 'tempest.scenario.test_network_basic_ops.TestNetworkBasicOps.test_mtu_sized_frames'
     reason: 'Test is failing, it is being investigated'
     lp: 'https://bugs.launchpad.net/tripleo/+bug/1731988'
+  - test: 'neutron.tests.tempest.scenario'
+    reason: 'Neutron tempest plugin scenario tests are unstable'
+    lp: 'https://launchpad.net/bugs/1737940'