Remove tap-as-a-service-tempest-plugin

tap-as-a-service-tempest-plugin tests were moved to
neutron-tempest-plugin when tap-as-a-service was
revived from x/, so this tempest plugin can be
removed from generate-tempest-plugins-list.py

Change-Id: I0a796b9bd5206092d5aee583db89c4227c626ff8
diff --git a/tools/generate-tempest-plugins-list.py b/tools/generate-tempest-plugins-list.py
index 0b6b342..2e8ced5 100644
--- a/tools/generate-tempest-plugins-list.py
+++ b/tools/generate-tempest-plugins-list.py
@@ -75,7 +75,6 @@
     'x/networking-l2gw-tempest-plugin'
     'x/novajoin-tempest-plugin'
     'x/ranger-tempest-plugin'
-    'x/tap-as-a-service-tempest-plugin'
     'x/trio2o'
     # No changes are merging in this
     # https://review.opendev.org/q/project:x%252Fnetworking-fortinet