Remove openstack/database-api from list of projects

The Trove database-api docs have been moved out of the
openstack/database-api repository and into the openstack/trove
repository, so we no longer need openstack/database-api.

Change-Id: Icbca1a349d61286ef74e9e55df057d86cd8cbd85
Merge "Remove openstack/database-api from list of projects"