update kafka bulk metadata options

[Gallardot]

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Description

update kafka bulk metadata options

ref: https://docs.dapr.io/developing-applications/building-blocks/pubsub/pubsub-bulk/#subscribing-messages-in-bulk
ref: https://github.com/dapr/components-contrib/blob/1132db59d61847cd517b905a8c257a5ab334f19a/pubsub/requests.go#L99

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