p2p: increase queue size to 16MB (#6588)

internal/p2p/queue.go

@@ -4,6 +4,9 @@ import (
 	tmsync "github.com/tendermint/tendermint/internal/libs/sync"
 )
 
+// default capacity for the size of a queue
+const defaultCapacity uint = 16e6 // ~16MB
+
 // queue does QoS scheduling for Envelopes, enqueueing and dequeueing according
 // to some policy. Queues are used at contention points, i.e.:
 //