Almost all proxy APIs were deprecated in microversion 2.36.
But the sub-resource image-metadata of image was forgotten to deprecate.
This patch deprecates the image-metdata API from 2.39.
Image commands were already deprecated since 2.36 in
I450917f7fcbfe0a3ea7921c82af9863e80cb40a1
Implements blueprint deprecate-image-meta-proxy-api
Change-Id: Idd4cd1d1fec13f9e5f89dc419b57e094c9ad4b3b