Complete the reconfigure optimise action for iscsi

Co-Authored-By: caoyuan <cao.yuan@99cloud.net>
Co-Authored-By: mgoddard <mark@stackhpc.com>

Change-Id: I6a1f24bc13bdea148857de9e6f4df79ff97bc9bc
Partially-implements: blueprint better-reconfigure
Closes-Bug: #1772215