treewide: remove unnecessary use of fmt.Sprint

Change-Id: I619dcf56665365e09be27e7c58b8b3596715b8b4
Reviewed-on: https://review.monogon.dev/c/monogon/+/3016
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
Vouch-Run-CI: Tim Windelschmidt <tim@monogon.tech>
diff --git a/metropolis/node/core/main.go b/metropolis/node/core/main.go
index ba760f7..9a7e39e 100644
--- a/metropolis/node/core/main.go
+++ b/metropolis/node/core/main.go
@@ -256,7 +256,7 @@
 	crash <- ""
 	crash <- ""
 	crash <- fmt.Sprintf(" Fatal error: %v", err)
-	crash <- fmt.Sprintf(" This node could not be started. Rebooting...")
+	crash <- " This node could not be started. Rebooting..."
 	time.Sleep(time.Second)
 	// Return to minit, which will reboot this node.
 	os.Exit(0)