Reduce number of calls to fetch time in the main loop (#8804)

esphome/components/debug/debug_component.cpp

@@ -70,7 +70,7 @@ void DebugComponent::loop() {
 #ifdef USE_SENSOR
   // calculate loop time - from last call to this one
   if (this->loop_time_sensor_ != nullptr) {
-    uint32_t now = millis();
+    uint32_t now = App.get_loop_component_start_time();
     uint32_t loop_time = now - this->last_loop_timetag_;
     this->max_loop_time_ = std::max(this->max_loop_time_, loop_time);
     this->last_loop_timetag_ = now;