Disable test_established_tcp_session_after_re_attachinging_sg in LB job

This test is failing from time to time in the Linuxbridge scenario job
so let's exclude it in that job until related bug will be fixed.

Related-Bug: #1936911
Change-Id: Ic89c65cf225bb7813001311b4625e7117b70f91c
diff --git a/zuul.d/master_jobs.yaml b/zuul.d/master_jobs.yaml
index a775711..20f76ec 100644
--- a/zuul.d/master_jobs.yaml
+++ b/zuul.d/master_jobs.yaml
@@ -303,7 +303,13 @@
       network_available_features: *available_features
       # TODO(eolivare): remove VLAN Transparency tests from blacklist
       # when bug https://bugs.launchpad.net/neutron/+bug/1907548 will be fixed
-      tempest_exclude_regex: "(^neutron_tempest_plugin.scenario.test_vlan_transparency.VlanTransparencyTest)"
+      # TODO(slaweq): remove
+      # test_established_tcp_session_after_re_attachinging_sg from the
+      # exclude regex when bug https://bugs.launchpad.net/neutron/+bug/1936911
+      # will be fixed
+      tempest_exclude_regex: "\
+          (^neutron_tempest_plugin.scenario.test_vlan_transparency.VlanTransparencyTest)|\
+          (^neutron_tempest_plugin.scenario.test_security_groups.NetworkSecGroupTest.test_established_tcp_session_after_re_attachinging_sg)"
       devstack_localrc:
         Q_AGENT: linuxbridge
         NETWORK_API_EXTENSIONS: "{{ (network_api_extensions + network_api_extensions_linuxbridge) | join(',') }}"