Remove contrib/block-box from zuul config
Remove contrib/block-box from zuul config

This doesn't need to be listed in "irrelevant-files"
since it isn't in the tree as of Iaa3a7892.

Change-Id: Ibd6e67caa27201cd564a6a344946b34bd530a1da

mahak/cinder,openstack/cinder,mahak/cinder,openstack/cinder