Do not ping event targets during cluster initialization (#19959)

S3 operations are frozen during startup, therefore we should avoid pinging
event targets during the initialization since it can stall.

cmd/server-startup-msg.go

@@ -158,7 +158,7 @@ func printEventNotifiers() {
 		return
 	}
 
-	arns := globalEventNotifier.GetARNList(true)
+	arns := globalEventNotifier.GetARNList()
 	if len(arns) == 0 {
 		return
 	}