Remove files that are part of openstack-doc-tools

cleanup/* and sitemap/* are part of openstack-doc-tools now, remove
them here.

Note: We cannot remove the whole tools directory yet until all gate jobs
are changed.

Change-Id: I2b810eeb3b9b623ebcafc33defd39251b8dc5ade
Merge "Remove files that are part of openstack-doc-tools"