Upgrade from 3.17 to 3.18
See NXBT-2944 which upgraded Nexus from 3.16.2 to 3.18.1
NXBT-3063 Upgrade nexus packages to 3.19.1
NXBT-3048 Allow Nuxeo developer pushing to the central Docker registry
NXBT-3045 Setup cleanup policies on Nexus