Enable universe repository on Ubuntu

The universe repository is not enabled when installing Ubuntu from an
ISO (at least for Bionic). This leads to some errors during the devstack
run that are not seen when running based on a cloud image which has that
repo enabled by default. Enable that repository unconditionally, the
operation is idempotent.

Change-Id: Ifcb7ecd78fb25ca2136f5848c19b74500e520873
Closes-Bug: 1792936
1 file changed