contrib/jenkins.sh: run "make maintainer-clean"
contrib/jenkins.sh: run "make maintainer-clean"

Related: OS#3047
Change-Id: I9d9b2412f005e4bda0ed35ba715cfb4dca1b04c1

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts