ipn/localapi: don't indent status response

Doing indented JSON marshaling results in encoding/json
allocating an internal buffer, so even when encoding directly
to a writer, it still generates a lot of garbage.

Updates tailscale/corp#18514

Signed-off-by: Percy Wegmann <percy@tailscale.com>

ipn/localapi/localapi.go

@@ -1202,9 +1202,7 @@ func (h *Handler) serveStatus(w http.ResponseWriter, r *http.Request) {
 	} else {
 		st = h.b.StatusWithoutPeers()
 	}
-	e := json.NewEncoder(w)
-	e.SetIndent("", "\t")
-	e.Encode(st)
+	json.NewEncoder(w).Encode(st)
 }
 
 func (h *Handler) serveDebugPeerEndpointChanges(w http.ResponseWriter, r *http.Request) {