[logger] Make tx_buffer_ compile-time sized (#14205)

tests/dummy_main.cpp

@@ -13,7 +13,7 @@ using namespace esphome;
 
 void setup() {
   App.pre_setup("livingroom", "LivingRoom", false);
-  auto *log = new logger::Logger(115200, 512);  // NOLINT
+  auto *log = new logger::Logger(115200);  // NOLINT
   log->pre_setup();
   log->set_uart_selection(logger::UART_SELECTION_UART0);
   App.register_component(log);