Mark the Nimble Driver Unsupported

The Nimble Driver 3rd Party CI hasn't run successfully
in 133 days.  This does not meet the requirements
for Cinder's 3rd Party CI requirements.

As a result the driver is being marked unsupported in the
Train release and should be removed in the 'U' release if
the problems are not resolved.

Change-Id: I801a887adf2db8cd5d14eaa77ebb1a1bf201ae99

cinder/volume/drivers/nimble.py

@@ -137,6 +137,9 @@ class NimbleBaseVolumeDriver(san.SanDriver):
     # ThirdPartySystems wiki page
     CI_WIKI_NAME = "Nimble_Storage_CI"
 
+    # TODO(jsbryant) Remove driver in the 'U' release if CI is not fixed.
+    SUPPORTED = False
+
     def __init__(self, *args, **kwargs):
         super(NimbleBaseVolumeDriver, self).__init__(*args, **kwargs)
         self.APIExecutor = None

doc/source/reference/support-matrix.ini

@@ -246,7 +246,7 @@ driver.netapp_ontap=complete
 driver.netapp_solidfire=complete
 driver.nexenta=complete
 driver.nfs=complete
-driver.nimble=complete
+driver.nimble=missing
 driver.oracle_zfssa=complete
 driver.prophetstor=complete
 driver.pure=complete

releasenotes/notes/nimble-mark-usnsupported-0c8e5e21c8d1179d.yaml

@@ -0,0 +1,14 @@
+---
+upgrade:
+  - |
+    The Nimble driver has been marked as unsupported and is now
+    deprecated. ``enable_unsupported_driver`` will need to be set
+    to ``True`` in the driver's section in cinder.conf to continue
+    to use it.
+deprecations:
+  - |
+    The Nimble driver has been marked as unsupported and is now
+    deprecated. ``enable_unsupported_driver`` will need to be set
+    to ``True`` in the driver's section in cinder.conf to continue
+    to use it. If its support status does not change, it will be
+    removed in the 'U' development cycle.