Remove old Heat hosts entries in tripleo-hosts-entries

For upgrades, this role now takes care of removing the old Heat entries
if they are present in /etc/hosts. The test prepare process has been
updated to create a temp file that would replicate what we'd expect
in a live system.

Change-Id: Ifc4d9553b74e6e6a9794902b418f54c0cfc7a39d

tripleo_ansible/roles/tripleo-hosts-entries/molecule/default/prepare.yml

@@ -14,8 +14,16 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-
 - name: Prepare
   hosts: all
   roles:
     - role: test_deps
+  post_tasks:
+    - name: Create temp host file
+      copy:
+        content: |
+          HEAT_HOSTS_START - Do not edit manually within this section!
+          0.0.0.0 test test.domain.local
+          0.0.0.1 test test.domain.local
+          HEAT_HOSTS_END
+        dest: "{{ tripleo_hosts_entries_hosts_path }}"

tripleo_ansible/roles/tripleo-hosts-entries/tasks/main.yml

@@ -14,6 +14,19 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+
+- name: Remove old Heat hosts configuration (if present)
+  become: true
+  blockinfile:
+    state: absent
+    path: "{{ tripleo_hosts_entries_hosts_path }}"
+    block: ""
+    marker: "# {mark}"
+    marker_begin: "HEAT_HOSTS_START - Do not edit manually within this section!"
+    marker_end: "HEAT_HOSTS_END"
+  tags:
+    - tripleo_hosts_entries
+
 - name: Update /etc/hosts
   become: true
   blockinfile: