TBR: services/allocator/allocatord: Make shorter instance names

Four bytes should be enough.

Change-Id: I74ca0fbcd54dd5acd56ff56fd059bcd4f54e6adf
diff --git a/services/allocator/allocatord/names.go b/services/allocator/allocatord/names.go
index c1ad7b1..4a5567e 100644
--- a/services/allocator/allocatord/names.go
+++ b/services/allocator/allocatord/names.go
@@ -25,7 +25,7 @@
 // newKubeName returns a new kubernetes name.
 func newKubeName() (string, error) {
 	// Kubernetes names/labels are at most 63 characters long.
-	b := make([]byte, 16)
+	b := make([]byte, 4)
 	if _, err := rand.Read(b); err != nil {
 		return "", err
 	}