p2p: remove wdrr queue (#7064)

This code hasn't been battle tested, and seems to have grown
increasingly flaky int tests. Given our general direction of reducing
queue complexity over the next couple of releases I think it makes
sense to remove it.

test/e2e/pkg/testnet.go

@@ -347,7 +347,7 @@ func (n Node) Validate(testnet Testnet) error {
 		return fmt.Errorf("invalid mempool version %q", n.Mempool)
 	}
 	switch n.QueueType {
-	case "", "priority", "wdrr", "fifo":
+	case "", "priority", "fifo":
 	default:
 		return fmt.Errorf("unsupported p2p queue type: %s", n.QueueType)
 	}