The archive_deleted_rows command in nova-manage is often-broken and
not well tested by us. We can test it to some degree in functional tests,
but running it against a real database with real deleted stuff in it
is a good idea. This adds a post-test hook and runs the archive so that
after a full test run in the gate, we'll see the output. Later, we should
make a failed run of this fatal, but for now, just run it so we can see
how close we are to being able to gate on it.
Change-Id: I16b2e00eede6af455cb74ca4e6ca951d56fdbcbc
6f988105ac