feat: use single GatewayStreamer object for all gateways in the CompositeGateway

[girishc13]

The GatewayStreamer object is instantiated in the BaseGateway. The CompositeGateway itself is a sub class of the BaseGateway and the respective protocol specific Gateway is also a sub class of the BaseGateway. Which means that there is at least one streamer object for the CompositeGateway class and one for each protocol specific gateway. This complicates the warmup logic (#5467) because by default only the CompositeGateway streamer object is being triggered. Using a single streamer object is more compact and reduces the overhead of creating multiple connection pools within each streamer object.