purge-cluster: remove all include tasks

purge-cluster: remove all include tasks

Including variables from role defaults or files in a group_vars
directory relative to the playbook is a bad practice. We don't want to
do this because including these defaults at the task level overrides
values that would be set in a group_vars directory relative to the
inventory file, which is the correct usage if you wish to override
those default values.

Signed-off-by: Andrew Schoen <aschoen@redhat.com>