tests/qtest/migration: Do proper cleanup in the dirty_limit test

The dirty_limit test does two migrations in a row and is leaking the
first 'to' instance. Do proper cleanup.

Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20241209204427.17763-2-farosas@suse.de>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
1 file changed