Replace lib-forward-testing-plugin

This repo is the only user of lib-forward-testing-plugin template,
replace it with a native integration job that installs all repos from
source and runs ceilometer - as the only job in
lib-forward-testing-plugin does.

Change-Id: I255c0ddd220633b566b9376473ede4b7ed16ca34

.zuul.yaml

@@ -1,7 +1,18 @@
+- job:
+    name: ceilometermiddleware-integration
+    parent: telemetry-dsvm-integration
+    required-projects:
+      - openstack/ceilometermiddleware
+
 - project:
     templates:
       - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
-      - lib-forward-testing-plugin
+    check:
+      jobs:
+        - ceilometermiddleware-integration
+    gate:
+      jobs:
+        - ceilometermiddleware-integration