all: fix full-tree golangci-lint findings

The new full-tree golangci-lint check reports issues the --new-from-rev
diff lint hid: nine wsl_v5 whitespace gaps, a prealloc, and an unparam
(setCSRFCookie never errored, so drop the return and update callers).
gocyclo on the central UpdateNodeFromMapRequest and an SA1019 NetMap
deprecation in an integration helper are suppressed with reasons.

cmd/headscale/cli/nodes.go

@@ -146,6 +146,7 @@ var listNodeRoutesCmd = &cobra.Command{
 		}
 
 		nodes := resp.JSON200.Nodes
+
 		if identifier != 0 {
 			idStr := strconv.FormatUint(identifier, util.Base10)
 			for _, node := range nodes {