Fixes race cond between delete and confirm resize

If we delete an instance after a confirming resize operation,
and if the instance is deleted firstly at the dest compute node,
then the *_resize dir and network info of this instance will be
left alone on the source compute node, never be cleaned up.
Please refer the bug page to get the reproduce steps

Fixes bug 1202484

Change-Id: Ib1e3d976373bd7f4d086d4f9716b0bca4b383bab
Merge "Fixes race cond between delete and confirm resize"