virt: delete unused 'interface_stats' method

The only use of the virt driver 'interface_stats' method was
removed 3+ years ago by

  commit 07646e85841a4f7c81e80254ac63715bece2aadd
  Author: Brian Waldon <brian.waldon@rackspace.com>
  Date:   Tue Aug 2 10:09:58 2011 -0400

    removing compute monitor

Change-Id: Ie43ebea3ecabd0dd11a5c341bf2310a00f143031
virt: Convert more tests to use instance objects

Update a couple of methods in test_virt_drivers so that they
use instance objects instead of dicts

Blueprint: libvirt-driver-class-refactor
Change-Id: Ib2257ac97c533a8a0d7f45994d21a67d08444e19
Updated from global requirements

Change-Id: I0d572918d958bcff6ab15af9ccea09401e53ebac
Fix base obj_make_compatible() handling ListOfObjectsField

This makes the base class' obj_make_compatible() handle lists of
objects properly.

Related to blueprint kilo-objects

Change-Id: Iaff1b435819e9aefcd2b362c846c87f9efa3f618
Make objects use the generalized backport scheme

This makes the objects that have subobjects use the base class'
obj_make_compatible() implementation for backports.

Related to blueprint kilo-objects

Change-Id: I106cd57001f028de7cc8ce7c7024809bceaed020
Merge "Fix base obj_make_compatible() handling ListOfObjectsField"
Merge "Updated from global requirements"
Merge "virt: delete unused 'interface_stats' method"
Merge "virt: Convert more tests to use instance objects"
Merge "Make objects use the generalized backport scheme"
VMware: Support volume hotplug

When a volume is attached to an instance, the disk_type and
adapter_type are found by making a get_dynamic_property vim
call to the instance. If the adapter_type returned is
"ide", the volume attach fails with "operation cannot be
performed in the current state". This is because VMware IDE
adapter does not support disk hotplug.

Instead of making a get_dynamic_property vim call to the
instance, it should be made to the volume (shadow VM). This
properly indicates what adapter_type is needed by the volume.
If the instance does not have a controller to support the
volume adapter_type (e.g. lsiLogic), one will be added.
If the volume adapter_type is "ide", a exception.Invalid will
be thrown.

Change-Id: Id826a33298885e9dbd4b52c9fe518ed2e6d50469
Closes-Bug: #1226543
Merge "VMware: Support volume hotplug"