Add ctlplane_masquerade for fs21 failing in ovb for ntp issue

This adds ctlplane_masquerade: true for f21 which is used by
periodic-tripleo-ci-centos-7-ovb-1ctlr_1comp-featureset021-master
As reported in the bug below this job fails as the compute node
can't reach pool.ntp.org

Change-Id: Ib146eaaefb202f1303454b5b86a33b6de8a096f1
Closes-Bug: 1794258

config/general_config/featureset021.yml

@@ -102,4 +102,9 @@ tempest_workers: 3
 # Install the latest unlreleased packages from CentOS
 enable_centos_cr_repo: true
 
-
+ctlplane_masquerade: >-
+  {% if release not in ['newton','ocata','pike','queens'] -%}
+  true
+  {%- else -%}
+  false
+  {%- endif -%}