recipe/libcloud: minimal fix for ImportError

This code error when it's imported, because it imports from a non existing,
slapos.tool module.
This is an "emergency commit" to repair the tests on python 3 after
 3a1e5628 (software/slapos-sr-testing: use nxdtest, 2020-10-28)

slapos/recipe/libcloud/__init__.py

@@ -4,7 +4,6 @@ import sys
 import zc.buildout
 import zc.recipe.egg
 from slapos.slap.slap import ServerError
-from slapos.tool.cloudmgr.cloudinterface import NodeInterface
 from pprint import pformat
 class SlavePartitionError(Exception):
   pass
@@ -87,6 +86,8 @@ class Recipe(BaseSlapRecipe):
       node_uuid = connection_dict.get('node_uuid', None),
       ssh_key = connection_dict.get('ssh_key', None)
     )
+    # FIXME: this import no longer exist
+    from slapos.tool.cloudmgr.cloudinterface import NodeInterface
     node = NodeInterface(**node_kw)
     update_kw = dict(
       image = requested_dict['image'],