packaging: setup: Generate answer file at cleanup

Generate answer file at end of stage Cleanup instead of stage Closeup.

Stage Cleanup is always executed at the end of the run, so the answer
file will always be generated - even if e.g. user chooses 'Cancel' at
the end of "CONFIGURATION PREVIEW", or presses ^C at any point.

Change-Id: I4b6af75001eb3192e6839e57dbb7446344ff29f4
Bug-Url: https://bugzilla.redhat.com/1077114
Signed-off-by: Yedidyah Bar David <didi@redhat.com>