Disable steppers on M112 (#15065)

And change verbiage to not refer to "Emergency Stop."

Marlin/src/gcode/control/M108_M112_M410.cpp

@@ -38,10 +38,10 @@ void GcodeSuite::M108() {
 }
 
 /**
- * M112: Emergency Stop
+ * M112: Full Shutdown
  */
 void GcodeSuite::M112() {
-  kill();
+  kill(PSTR("M112 Shutdown"), true);
 }
 
 /**

Marlin/src/gcode/control/M80_M81.cpp

@@ -86,7 +86,7 @@
 /**
  * M81: Turn off Power, including Power Supply, if there is one.
  *
- *      This code should ALWAYS be available for EMERGENCY SHUTDOWN!
+ *      This code should ALWAYS be available for FULL SHUTDOWN!
  */
 void GcodeSuite::M81() {
   thermalManager.disable_all_heaters();