Remove unneeded and expired Swift artifacts

Issue

• During overcloud deployment, we receive an error due to expired Swift artifacts:

stack.AllNodesDeploySteps.ComputeArtifactsDeploy.7:
  resource_type: OS::Heat::StructuredDeployment
  physical_resource_id: 8a4ba8d9-6243-46a9-a87d-3d5212334b3e
  status: CREATE_FAILED
  status_reason: |
    Error: resources[7]: Deployment to server failed: deploy_status_code : Deployment exited with non-zero status code: 1
  deploy_stdout: |
    ERROR: Unsupported file format: http://192.168.24.1:8080/v1/AUTH_2490b1819190483e9167573f7bac0f76/overcloud-artifacts/myfile.tar.gz?temp_url_sig=c06be32c5af96bc26e819638c0bf05b9d06cffdf&temp_url_expires=1583208153