Fix node initialization in test

The topological consensus tests were supposed to have the instances initialized with a random tree of blocks,
where each block points to a random set of descendants.

Instead, because of a bug that influenced the parent reference, the blocks were added to the consensus instance
as a single block with the rest of the blocks as descendants.

That's not what we want to test, so this commit fixes this and further simplifies the initialization logic.

Signed-off-by: Yacov Manevich <yacov.manevich@avalabs.org>

snow/consensus/snowman/network_test.go

@@ -74,26 +74,20 @@ func (n *Network) AddNode(t testing.TB, sm Consensus) error {
 	}
 
 	n.shuffleColors()
-	deps := map[ids.ID]ids.ID{}
 	for _, blk := range n.colors {
-		myDep, found := deps[blk.ParentV]
-		if !found {
-			myDep = blk.Parent()
-		}
 		myBlock := &snowmantest.Block{
 			Decidable: snowtest.Decidable{
 				IDV:    blk.ID(),
 				Status: blk.Status,
 			},
-			ParentV: myDep,
+			ParentV: blk.ParentV,
 			HeightV: blk.Height(),
 			VerifyV: blk.Verify(context.Background()),
 			BytesV:  blk.Bytes(),
 		}
 		if err := sm.Add(myBlock); err != nil {
 			return err
 		}
-		deps[myBlock.ID()] = myDep
 	}
 	n.nodes = append(n.nodes, sm)
 	n.running = append(n.running, sm)