Remove unused and duplicate nodeset defined in Tempest
Remove unused and duplicate nodeset defined in Tempest

Below nodesets defined in Tempest are removed now:

- openstack-bionic-node This is unused after I5a24c697103090f6712d6e9168abe6c86f7c380c
- openstack-opensuse150-node is duplicate of devstack-single-node-opensuse-150

Depends-On: https://review.openstack.org/#/c/641746/

Change-Id: I39c03bfa52191a0b1acf6a73fa31b3c071ee60c1

openstack/tempest,masayukig/tempest,masayukig/tempest,cisco-openstack/tempest,cisco-openstack/tempest,openstack/tempest