Cleanup unused CI tooling (#11014)

tests/Makefile

tests/README.md

tests/cloud_playbooks/create-aws.yml

tests/cloud_playbooks/create-do.yml

tests/cloud_playbooks/delete-aws.yml

tests/cloud_playbooks/templates/boto.j2

tests/cloud_playbooks/templates/gcs_life.json.j2

tests/local_inventory/host_vars/localhost

tests/local_inventory/hosts.cfg

tests/requirements.yml

tests/scripts/ansibl8s_test.sh

tests/support/aws.groovy

tests/templates/inventory-aws.j2

tests/templates/inventory-do.j2

tests/templates/inventory-gce.j2