jobs/master: add workspace.tar.xz to artifacts

Upload workspace.tar.xz if it was created by osmo-bsc or osmo-msc, after
the testsuite failed. This should help with figuring out why sometimes
we get a coredump.

Related: OS#5665
Change-Id: I40b738558b83efc9256e5d5c48ffce42ddce9a8a
1 file changed