Drop testing of SaltStack 2016.3

Change-Id: I5ea0ffa5d3f2221a5db9cfee1d5f17bfa48acee7
Related: PROD-27314 (PROD:27314)
diff --git a/.kitchen.yml b/.kitchen.yml
index 61b5361..b9372dc 100644
--- a/.kitchen.yml
+++ b/.kitchen.yml
@@ -37,19 +37,10 @@
   sudo: true
 
 docker_images:
-  - &trusty-20163 <%=ENV['IMAGE_TRUSTY_20163'] || 'docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-trusty-salt-2016.3/salt:2018_11_19'%>
-  - &trusty-20177 <%=ENV['IMAGE_TRUSTY_20177'] || 'docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-trusty-salt-2017.7/salt:2018_11_19'%>
-  - &trusty-stable <%=ENV['IMAGE_TRUSTY_STABLE'] || 'docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-trusty-salt-stable/salt:2018_11_19'%>
-  - &xenial-20163 <%=ENV['IMAGE_XENIAL_20163'] || 'docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2016.3/salt:2018_11_19'%>
   - &xenial-20177 <%=ENV['IMAGE_XENIAL_20177'] || 'docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2017.7/salt:2018_11_19'%>
   - &xenial-stable <%=ENV['IMAGE_XENIAL_STABLE'] || 'docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-stable/salt:2018_11_19'%>
 
 platforms:
-  - name: xenial-2016.3
-    driver_config:
-      image: *xenial-20163
-      platform: ubuntu
-
   - name: xenial-2017.7
     driver_config:
       image: *xenial-20177