Prevent watchdog reset in setup() (#21776)

Cause `manage_heaters` to only reset the watchdog and return until `setup()` is completed.

Co-authored-by: Scott Lahteine <github@thinkyhead.com>

Marlin/src/inc/Conditionals_adv.h

   #endif
 #endif
 
-// If platform requires early initialization of watchdog to properly boot
-#if ENABLED(USE_WATCHDOG) && defined(ARDUINO_ARCH_SAM)
-  #define EARLY_WATCHDOG 1
-#endif
-
 // Full Touch Screen needs 'tft/xpt2046'
 #if EITHER(TOUCH_SCREEN, HAS_TFT_LVGL_UI)
   #define HAS_TFT_XPT2046 1

Marlin/src/module/temperature.cpp

 
 // private:
 
-#if EARLY_WATCHDOG
-  bool Temperature::inited = false;
-#endif
-
 volatile bool Temperature::raw_temps_ready = false;
 
 #if ENABLED(PID_EXTRUSION_SCALING)
  *  - Update the heated bed PID output value
  */
 void Temperature::manage_heater() {
-
-  #if EARLY_WATCHDOG
-    // If thermal manager is still not running, make sure to at least reset the watchdog!
-    if (!inited) return watchdog_refresh();
-  #endif
+  if (marlin_state == MF_INITIALIZING) return watchdog_refresh(); // If Marlin isn't started, at least reset the watchdog!
 
   #if ENABLED(EMERGENCY_PARSER)
     if (emergency_parser.killed_by_M112) kill(M112_KILL_STR, nullptr, true);
     TERN_(TEMP_SENSOR_1_IS_MAX6675, max6675_1.begin());
   #endif
 
-  #if EARLY_WATCHDOG
-    // Flag that the thermalManager should be running
-    if (inited) return;
-    inited = true;
-  #endif
-
   #if MB(RUMBA)
     // Disable RUMBA JTAG in case the thermocouple extension is plugged on top of JTAG connector
     #define _AD(N) (TEMP_SENSOR_##N##_IS_AD595 || TEMP_SENSOR_##N##_IS_AD8495)
   #endif
 
   // Wait for temperature measurement to settle
-  delay(250);
+  //delay(250);
 
   #if HAS_HOTEND
 

Marlin/src/module/temperature.h

 
   private:
 
-    #if ENABLED(EARLY_WATCHDOG)
-      static bool inited;   // If temperature controller is running
-    #endif
-
     static volatile bool raw_temps_ready;
 
     #if ENABLED(WATCH_HOTENDS)