Using host_prep_tasks interface to handle undercloud teardown before we
run the undercloud install.
The reason of not using upgrade_tasks is because the existing tasks were
created for the overcloud upgrade first and there are too much logic
right now so we can easily re-use the bits for the undercloud. In the
future, we'll probably use upgrade_tasks for both the undercloud and
overcloud but right now this is not possible and a simple way to move
forward was to implement these tasks that work fine for the undercloud
containerization case.
Workflow will be:
- Services will be stopped and disabled (except mariadb)
- Neutron DB will be renamed, then mariadb stopped & disabled
- Remove cron jobs
- All packages will be upgraded with yum update.
Change-Id: I36be7f398dcd91e332687c6222b3ccbb9cd74ad2
d86025593b