Expand the metrics reporting of MTV with the storage offloads metrics by scraping the metrics exposed by the populator pods so customers can see how fast disks are cloned.

Currently we expose a 'progress' counter (there from 2.8) and with https://github.com/kubev2v/forklift/pull/2523 we will have a counter for the number of bytes copied using XCOPY. That will indicate if an efficient offloaded copy was in use or not, and if not we would like to reflect that (that could indicate infra errors/misconfiguratio in various places)

One caveat: the metric server runs in the background of the popualtor process, and when the populator terminates the scraping target may disappear before it can reflect matching number of bytes copied with xcopy. We can fix that by sleeping in the end a period which equals to the scraping interval. not a best solution, but could work. The scraping interval is not a shared value I guess, eventhough it goes under a configmap of some sort...