Don't delete tarballs in run-wheel.sh

run-wheel.sh was deleting tarballs created by run-tarball.sh in the same
job. This meant Jenkins could not copy the tarballs and the tarball jobs
fail. Stop deleting tarballs and delete wheels instead as part of pre
wheel generation house keeping.

Change-Id: I4a850a289726ea6d25c72cf275fbba5aa60289b2
partial-bug: #1325456
Merge "Don't delete tarballs in run-wheel.sh"