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/node/core/consensus/logparser.go b/metropolis/node/core/consensus/logparser.go
index c54968c..dbd3b1d 100644
--- a/metropolis/node/core/consensus/logparser.go
+++ b/metropolis/node/core/consensus/logparser.go
@@ -36,7 +36,7 @@
 		return
 	}
 
-	e := etcdLogEntry{}
+	var e etcdLogEntry
 	// Parse constant fields
 	if err := json.Unmarshal([]byte(l.Data), &e); err != nil {
 		write(&logtree.ExternalLeveledPayload{