jenkins: properly clean previous artifacts Drop the second 'rm -f' from the rm shell command (typo). Remove all artifacts matching *.build-*.{tgz,md5} because if a job changes the name of its artifact, the previous artifacts would remain. (I hit this with the new scripts being originally wrong and all producing 'osmo-msc.*' artifacts, and those stuck around in the workspace even after the name was fixed.) Change-Id: I00d246226f4c723696bb737ed707cfd0e4c33714
