use terraform workspaces for managing CI deployment states

[O1ahmad]

terraform workspace basically allows management of multiple related states via a single state file (see for more details).

Also reduce time after apply to destroy deployment during DeployAndDestroy test and add a variable for the path for testnet artifacts to be stored/processed locally.

Test: Buildkite CI

Checklist:

• Document code purpose, how to use it
  • Mention expected invariants, implicit constraints
• Tests were added for the new behavior
  • Document test purpose, significance of failures
  • Test names should reflect their purpose
• All tests pass (CI will check this if you didn't)
• Serialized types are in stable-versioned modules
• Does this close issues? List them:

Closes #7701

[O1ahmad]

remove trailing '/'