[gpio] Use a user provided default constructor for GPIOSwitch (#19203)

esphome/components/gpio/switch/gpio_switch.h

@@ -9,6 +9,9 @@ namespace esphome::gpio {
 
 class GPIOSwitch final : public switch_::Switch, public Component {
  public:
+  // User provided, not "= default": `new(p) GPIOSwitch()` would zero-fill .bss that is already zero.
+  GPIOSwitch() {}
+
   void set_pin(GPIOPin *pin) { pin_ = pin; }
 
   // ========== INTERNAL METHODS ==========
@@ -25,7 +28,7 @@ class GPIOSwitch final : public switch_::Switch, public Component {
  protected:
   void write_state(bool state) override;
 
-  GPIOPin *pin_;
+  GPIOPin *pin_{nullptr};
 #ifdef USE_GPIO_SWITCH_INTERLOCK
   FixedVector<Switch *> interlock_;
   uint32_t interlock_wait_time_{0};