Deprecate suppot for HPE Lefthand driver

... because the driver implementation was removed from cinder[1].

[1] 00519aef92

Change-Id: I566b097a9cfff9c8690fb90105422b05a7e3c73b

manifests/backend/hpelefthand_iscsi.pp

@@ -1,3 +1,4 @@
+# DEPRECATED !!
 # Configures Cinder volume HPE lefthand ISCSI driver.
 # Parameters are particular to each volume driver.
 #
@@ -63,6 +64,9 @@ define cinder::backend::hpelefthand_iscsi(
 
   include cinder::deps
 
+  warning('The support for HPE Lefthand 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-hpelefthand-support-4a42657e453a6c51.yaml

@@ -0,0 +1,5 @@
+---
+deprecations:
+  - |
+    The support for HPE Lefthand driver has been deprecated and will be removed
+    in a future release, in favor of removal of Lefthand driver from cinder.