Optimize the upload artifact process from agent to storage

Currently uploading the build artifact from qtbase build takes around 8-10 minutes, this is up to 2/3 of what some builds take. Installing the same artifact on the next build takes only 45 seconds. Uploading the testartifact takes up to 15 minutes in some instances and extracting this to test VM around 90 seconds. This means that the transfer is some 10 times less efficient from agent to storage than the other way.