[cleanup] Remove test-data for heat

This patch removes test-data to run integration test for heat
but heat is no longer a part of the horizon as it has a separate
plugin heat-dashboard. So this patch removes heat test-data.

Change-Id: Id2427c26dd8708b06b941fdd4e3cba0b2dd98808

openstack_dashboard/test/integration_tests/tests/test-data/stack_template

@@ -1,11 +0,0 @@
-heat_template_version: 2013-05-23
-description: Simple template to deploy a single compute instance
-resources:
-      my_instance:
-        type: OS::Nova::Server
-        properties:
-          key_name: {0}
-          image: {1}
-          flavor: m1.tiny
-          networks:
-            - network: {2}