Remove uml virt type support

... because nova already removed support for UML(User Mode Linux)[1]

[1] d02ce3c4f0efe6c437b0d22ea17afdd713e45d43

Change-Id: I3054aa69db89da58cdc547d6a0f4b3c9ec5d3443

ceilometer/compute/virt/libvirt/utils.py

@@ -30,7 +30,7 @@ LOG = logging.getLogger(__name__)
 OPTS = [
     cfg.StrOpt('libvirt_type',
                default='kvm',
-               choices=['kvm', 'lxc', 'qemu', 'parallels', 'uml'],
+               choices=['kvm', 'lxc', 'qemu', 'parallels'],
                help='Libvirt domain type.'),
     cfg.StrOpt('libvirt_uri',
                default='',
@@ -39,7 +39,6 @@ OPTS = [
 ]
 
 LIBVIRT_PER_TYPE_URIS = dict(
-    uml='uml:///system',
     parallels='parallels:///system',
     lxc='lxc:///')
 

releasenotes/notes/remove-uml-e86feeabdd16c628.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    The ``[DEFAULT] virt_type`` option no longer supports ``uml``. UML support
+    by nova was removed in nova 23.3.0 release.