Remove deprecated rpc_backend param

Remove the deprecated rpc_backend param which has been deprecated for
two years. The default_transport_url has been present for a while
now and should be used.

Change-Id: I0b1356b3e44c3f01fb7025fa8f0720403dd376da

manifests/init.pp

@@ -297,11 +297,6 @@
 #   (Optional) Maximum number of RabbitMQ connection retries. (integer value)
 #   Defaults to undef
 #
-# [*rpc_backend*]
-#   (optional) The messaging driver to use, defaults to rabbit. Other drivers
-#   include amqp and zmq.
-#   Defaults to 'rabbit'.
-#
 # === Authors
 #
 # Daniel Pawlik  <daniel.pawlik@corp.ovh.com>
@@ -374,7 +369,6 @@ class watcher (
   $notification_topics                  = $::os_service_default,
   # DEPRECATED PARAMETERS
   $rabbit_max_retries                   = undef,
-  $rpc_backend                          = 'rabbit',
 ) {
 
   include ::openstacklib::openstackclient
@@ -389,10 +383,6 @@ class watcher (
     warning('The rabbit_max_retries parameter has been deprecated and will be removed in the future release.')
   }
 
-  if $rpc_backend {
-    warning('The rpc_backend parameter has been deprecated, please use default_transport_url instead.')
-  }
-
   package { 'watcher':
     ensure => $package_ensure,
     name   => $::watcher::params::common_package_name,

releasenotes/notes/remove-deprecated-rabbit-params-a34e86d1c1d0a6fc.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    The deprecated watcher::rpc_backend is now removed. Please use
+    watcher::default_transport_url instead.