opal-ci: 18.04: Go back to updating before installing packages
opal-ci: 18.04: Go back to updating before installing packages

Docker tries to cache stuff and it bites us.

Signed-off-by: Joel Stanley <4816dabf8db1bc6cac35b3a24cab2ff844b5b0c7@jms.id.au>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.ibm.com>

open-power/skiboot,qemu/skiboot,open-power/skiboot,shenki/skiboot,qemu/skiboot,legoater/skiboot,open-power/skiboot,legoater/skiboot,open-power/skiboot,stewart-ibm/skiboot,stewart-ibm/skiboot,legoater/skiboot,shenki/skiboot,qemu/skiboot,legoater/skiboot,qemu/skiboot,qemu/skiboot,shenki/skiboot,shenki/skiboot,shenki/skiboot,stewart-ibm/skiboot,legoater/skiboot,open-power/skiboot