Improve quorum queue Ra system configurability #727

Job	Run time
Build old RabbitMQ	4m 7s
Build new RabbitMQ	4m 5s
Test transient_queue + 3 node(s)	1m 22s
Test topic_bindings_import + 3 node(s)	7m 28s
Test 10k_queues_import + 3 node(s)	2m 30s
Test topic_bindings_import + 1 node(s)	2m 28s
Test 10k_queues_import + 1 node(s)	1m 22s
Test durable_queue + 1 node(s)	46s
Test durable_queue + 3 node(s)	1m 27s
	25m 35s

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