As part of the work for configuring custom source_uri in Fleet UI, we need to be able to configure  agent.download.sourceURI in the Agent Policy, but at the moment the agent is not able to reload the policy at runtime. Could you help out with this feature?

The other option would be to pass the custom source_uri through the fleet-actions, but this would impact the scalability in the case of bulk upgrades (elastic/kibana#135579).