Fix kill => disable_all_heaters => print_job_timer.stop (#12146)

- Remove `print_job_timer.stop()` from `disable_all_heaters`
- Call `print_job_timer.stop()` for relevant `disable_all_heaters()`.
- Split up `kill()` for watchdog interrupt safety

Marlin/src/gcode/control/M108_M112_M410.cpp

@@ -41,7 +41,7 @@ void GcodeSuite::M108() {
  * M112: Emergency Stop
  */
 void GcodeSuite::M112() {
-  kill(PSTR(MSG_KILLED));
+  kill();
 }
 
 /**