[Resource Type] - [Enhancement] - Dynamic messageGroupId feature in AWS EventBus

### Name of the resource

AWS::Events::EventBus

### Resource name

_No response_

### Description

Hi Team,

We are requesting support for a dynamic messageGroupId feature in AWS EventBridge rules. Currently, the messageGroupId is statically set—often to a fixed value—which causes all messages routed to an AWS FIFO queue to share the same group ID. This results in significant processing inefficiencies, as the FIFO queue enforces strict ordering within a message group, allowing only a single consumer to process messages sequentially. Enabling dynamic assignment of messageGroupId would allow better parallelism and throughput by distributing messages across multiple message groups.

### Other Details

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