commander: battery failsafe action back to warning

This reverts a previous change because we're not entirely sure about all
implications on various airframes. It makes sense to change this default
after the failsafe state machines have been consolidated and the various
failsafe behaviours are more predictable for all airframes (not just
multicopter).

src/modules/commander/commander_params.c

@@ -323,7 +323,7 @@ PARAM_DEFINE_INT32(COM_ARM_SWISBTN, 0);
  * @decimal 0
  * @increment 1
  */
-PARAM_DEFINE_INT32(COM_LOW_BAT_ACT, 3);
+PARAM_DEFINE_INT32(COM_LOW_BAT_ACT, 0);
 
 /**
  * Time-out to wait when offboard connection is lost before triggering offboard lost action.