The original requirement from here: https://issues.redhat.com/browse/ACM-22400

Description

1. Enable event send mode configuration
Allow configuration of the event send mode (single or batch) by adding the annotation:

global-hub.open-cluster-management.io/event-send-mode=single|batch 

This can be applied to either the MultiClusterGlobalHub or MultiClusterGlobalHubAgent CR.

• single: the agent sends events one by one.
• batch: the agent sends aggregated event payloads.

2. Backward compatibility

Ensure the manager can handle both single and batch event formats for compatibility with existing deployments. The event include:

• root policy event
• managed cluster event
• replicated policy event