crashDetTimer can be ShortTimer

Expired value is less than 65535

Saves 8 bytes of flash and 2 bytes of SRAM

Firmware/Marlin_main.cpp

@@ -205,7 +205,7 @@ unsigned long pause_time = 0;
 unsigned long start_pause_print = _millis();
 unsigned long t_fan_rising_edge = _millis();
 LongTimer safetyTimer;
-static LongTimer crashDetTimer;
+static ShortTimer crashDetTimer;
 
 //unsigned long load_filament_time;