Use pigz and enable verbosity for tar when generating the upgrade artifact

[sdimitro]

similar to what we do for the migration image.

[basil]

Most of this task was covered in #267. There are just two more things that need to be done:

• Consistently enabling verbosity when calling tar(1). Right now there are still a few tar(1) invocations that don't use the -v flag.
• Making 90-linux-migration-artifact.binary invoke pigz(1) with the -I pigz argument to tar(1) rather than a pipe. As mentioned in #267, this would make all usage of pigz(1) consistent.