refactor(settings): strictly load orchestration settings only from system config directory

This MR ensures that orchestration settings are only loaded only from the system configuration /etc/juice/config/orchestration.toml and no longer from lab/config.
It can be tested by adding an orchestration.toml file to lab/config and then loading the OrchestrationSettings. Observe that the content is not being passed to the result.

from orangeqs.juice.orchestration.settings import OrchestrationSettings
OrchestrationSettings.load()