[Trivial]Remove unused helper get_allocated_disk_size

Helper get_allocated_disk_size is no longer used after
d41ea9d, this is to remove it.

Change-Id: Ib7a347b4fdb49fce893e227c72bdfbee4cea00ef

Author: zhufl

nova/tests/unit/virt/libvirt/test_driver.py

@@ -4932,8 +4932,7 @@ def test_detach_encrypted_volumes(self, mock_get_volume_size,
 
         @mock.patch.object(dmcrypt, 'delete_volume')
         @mock.patch.object(conn._host, '_get_domain', return_value=dom)
-        @mock.patch.object(libvirt_driver.disk_api, 'get_allocated_disk_size')
-        def detach_encrypted_volumes(block_device_info, mock_get_alloc_size,
+        def detach_encrypted_volumes(block_device_info,
                                      mock_get_domain, mock_delete_volume):
             conn._detach_encrypted_volumes(instance, block_device_info)
 

nova/virt/disk/api.py

@@ -107,16 +107,6 @@ def get_disk_size(path):
     return images.qemu_img_info(path).virtual_size
 
 
-def get_allocated_disk_size(path):
-    """Get the allocated size of a disk image
-
-    :param path: Path to the disk image
-    :returns: Size (in bytes) of the given disk image as allocated on the
-              filesystem
-    """
-    return images.qemu_img_info(path).disk_size
-
-
 def extend(image, size):
     """Increase image to size.