Removing juju installation in the jenkins pipeline

With the new way of the juju accces in k8s_08 testsuite,
installing juju in the container is not needed.
k8s_08 testsuite changes: https://osm.etsi.org/gerrit/c/osm/tests/+/11104



Change-Id: I7c5a59a776df23ca21b21a17728e658ad6d4e388
Signed-off-by: aktas <emin.aktas@ulakhaberlesme.com.tr>
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>