Blacklist x/kingbird project from sanity-check

x/kingbird doens't seem to be compatible with tempest anymore
which is breaking our tempest-tox-plugin-sanity-check gate job.

Change-Id: Icdaff49bbc2ba0e59cd528d55cad6c35014b7ad0
diff --git a/tools/generate-tempest-plugins-list.py b/tools/generate-tempest-plugins-list.py
index 64adcbe..c505908 100644
--- a/tools/generate-tempest-plugins-list.py
+++ b/tools/generate-tempest-plugins-list.py
@@ -49,6 +49,7 @@
     # https://review.opendev.org/#/c/637718/
     'openstack/neutron-vpnaas',  # https://review.opendev.org/#/c/637719/
     'x/valet',  # https://review.opendev.org/#/c/638339/
+    'x/kingbird',  # https://bugs.launchpad.net/kingbird/+bug/1869722
 ]
 
 url = 'https://review.opendev.org/projects/'