treewide: initialize empty structs with var

Change-Id: I72d3993eaf5fe57c77b1dda8218e36a8cc11813d
Reviewed-on: https://review.monogon.dev/c/monogon/+/3108
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/cli/metroctl/table_node.go b/metropolis/cli/metroctl/table_node.go
index 4af9f2c..37dbb48 100644
--- a/metropolis/cli/metroctl/table_node.go
+++ b/metropolis/cli/metroctl/table_node.go
@@ -13,7 +13,7 @@
 )
 
 func nodeEntry(n *apb.Node) clitable.Entry {
-	res := clitable.Entry{}
+	var res clitable.Entry
 
 	res.Add("node id", identity.NodeID(n.Pubkey))
 	state := n.State.String()