Revert "Import run_cross_tests.sh from oslo-incubator"

This reverts commit 6c0ad7c5f5fbd2a0808ce268b3ba29627b7682a3.

I'd like to wait to see what happens with https://review.openstack.org/#/c/95885/.

Change-Id: I736b632fb568a0c711b3cb0a91c22d74c811edc2
Merge "Revert "Import run_cross_tests.sh from oslo-incubator""