Removing deprecated function 'IPWrapper.get_namespaces()'

'IPWrapper.get_namespaces()' is deprecated in version 'Queens'
and was marked to be removed 'Rocky'.
This patch removes it and switches to use
'neutron.agent.linux.ip_lib.list_network_namespaces' instead.

Change-Id: I090cc5841aca5b638d08d65645162811950d6437
Depends-On: Id629481fd722004a7b7d827bf6209785f85f4c64

neutron/agent/linux/ip_lib.py

@@ -17,7 +17,6 @@ import os
 import re
 import time
 
-from debtcollector import removals
 import eventlet
 import netaddr
 from neutron_lib import constants
@@ -264,14 +263,6 @@ class IPWrapper(SubProcessBase):
         privileged.create_interface(name, self.namespace, "vxlan", **kwargs)
         return (IPDevice(name, namespace=self.namespace))
 
-    @removals.remove(version='Queens', removal_version='Rocky',
-                     message="This will be removed in the future. Please use "
-                             "'neutron.agent.linux.ip_lib."
-                             "list_network_namespaces' instead.")
-    @classmethod
-    def get_namespaces(cls):
-        return list_network_namespaces()
-
 
 class IPDevice(SubProcessBase):
     def __init__(self, name, namespace=None):

neutron/tests/functional/cmd/test_netns_cleanup.py

@@ -79,7 +79,7 @@ class NetnsCleanupTest(base.BaseSudoTestCase):
         netns_cleanup.cleanup_network_namespaces(self.conf)
 
         self.get_namespaces_p.stop()
-        namespaces_now = ip_lib.IPWrapper.get_namespaces()
+        namespaces_now = ip_lib.list_network_namespaces()
         procs_after = self._get_num_spawned_procs()
         self.assertEqual(procs_after, 0)
         self.assertNotIn(l3_namespace, namespaces_now)