Deprecate support for Nexenta Edge Driver

... because it was already removed from cinder[1].

[1] a1c58b50ea90986242afa9efe684bd5b87a39daf

Change-Id: Iabcc467f8c6bc43057c1efd4f487657b4b13c3d8

manifests/backend/nexenta_edge.pp

@@ -1,5 +1,6 @@
 # == Class: cinder::backend::nexenta_edge
 #
+# DEPRECATED!
 # Setups Cinder with Nexenta Edge volume driver.
 #
 # === Parameters
@@ -74,6 +75,9 @@ define cinder::backend::nexenta_edge (
   $extra_options             = {},
 ) {
 
+  warning('Support for Nexenta Edge Driver has been deprecated and will be removed \
+in a future release')
+
   cinder_config {
     "${name}/volume_backend_name":       value => $volume_backend_name;
     "${name}/backend_availability_zone": value => $backend_availability_zone;

releasenotes/notes/deprecate-nexenta-edge-b10e6c19c02d26eb.yaml

@@ -0,0 +1,5 @@
+---
+deprecations:
+  - |
+    Support for Nexenta Edge Driver has been deprecated and will be removed in
+    a future release.