[MIRROR] Basic mobs don't become dense upon death [MDB IGNORE] (#18679)

* Basic mobs don't become dense upon death (#72554)

## About The Pull Request

In #72260 what was previously a var became a flag, which was a sensible
change, however this inverted the default behaviour.
In virtually all cases we want dead mobs to _stop_ being dense, this
added a requirement for the flag to be present for that to happen and
then didn't add the flag to any mobs.

Rather than add this to every mob I inverted the function of the flag.
My reasoning here is that _simple_ mobs seemingly never required this
behaviour, basic mobs are probably going to need it rarely if ever, and
including it in `basic_mob_flags` by default seems messy and easy to
leave off when setting other flags (plus #72524 implies to me we want to
avoid adding more default values).

Setting this manually on each mob seems kind of silly as a requirement
going forward and I can't think of a way we'd unit test for people
forgetting.

For the same reason I did the same thing with the
`STOP_ACTING_WHILE_DEAD` flag I added to the AI controller in a recent
PR, the flag should denote unusual behaviour not the default.

## Why It's Good For The Game

It looks really odd when you're constantly shuffling places with dead
mobs, they're not supposed to do that.
It's tedious to add `STOP_ACTING_WHILE_DEAD` to every AI controller when
that should be an obvious default assumption.

## Changelog

🆑
fix: Dead basic mobs are no longer "dense" objects and can be stepped
on.
/🆑

* Basic mobs don't become dense upon death

* Removes a flag we didn't need anymore.

* Forgot to remove this one

Co-authored-by: Jacquerel <hnevard@gmail.com>
Co-authored-by: GoldenAlpharex <58045821+GoldenAlpharex@users.noreply.github.com>
Co-authored-by: GoldenAlpharex <jerego1234@hotmail.com>

code/modules/mob/living/basic/basic.dm

@@ -149,7 +149,7 @@
 	icon_state = icon_dead
 	if(basic_mob_flags & FLIP_ON_DEATH)
 		transform = transform.Turn(180)
-	if(basic_mob_flags & UNDENSIFY_ON_DEATH)
+	if(!(basic_mob_flags & REMAIN_DENSE_WHILE_DEAD))
 		set_density(FALSE)
 
 /mob/living/basic/revive(full_heal_flags = NONE, excess_healing = 0, force_grab_ghost = FALSE)
@@ -163,7 +163,7 @@
 	icon_state = icon_living
 	if(basic_mob_flags & FLIP_ON_DEATH)
 		transform = transform.Turn(180)
-	if(basic_mob_flags & UNDENSIFY_ON_DEATH)
+	if(!(basic_mob_flags & REMAIN_DENSE_WHILE_DEAD))
 		set_density(initial(density))
 
 /mob/living/basic/proc/melee_attack(atom/target, list/modifiers)

code/modules/mob/living/basic/farm_animals/cow/cow_ai.dm

@@ -5,7 +5,7 @@
 		BB_BASIC_MOB_TIPPER = null,
 	)
 
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 	planning_subtrees = list(

code/modules/mob/living/basic/farm_animals/pig.dm

@@ -51,7 +51,7 @@
 		BB_TARGETTING_DATUM = new /datum/targetting_datum/basic/ignore_faction(),
 	)
 
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 

code/modules/mob/living/basic/farm_animals/rabbit.dm

@@ -50,7 +50,7 @@
 		BB_BASIC_MOB_FLEEING = TRUE,
 		BB_TARGETTING_DATUM = new /datum/targetting_datum/basic/ignore_faction(),
 	)
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 	planning_subtrees = list(

code/modules/mob/living/basic/farm_animals/sheep.dm

@@ -85,7 +85,7 @@
 		BB_BASIC_MOB_FLEEING = TRUE,
 		BB_TARGETTING_DATUM = new /datum/targetting_datum/basic/ignore_faction(),
 	)
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 	planning_subtrees = list(

code/modules/mob/living/basic/vermin/axolotl.dm

@@ -36,6 +36,6 @@
 	ADD_TRAIT(src, TRAIT_VENTCRAWLER_ALWAYS, INNATE_TRAIT)
 
 /datum/ai_controller/basic_controller/axolotl
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk

code/modules/mob/living/basic/vermin/cockroach.dm

@@ -57,7 +57,7 @@
 		BB_PET_TARGETTING_DATUM = new /datum/targetting_datum/not_friends(),
 	)
 
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 	planning_subtrees = list(

code/modules/mob/living/basic/vermin/mothroach.dm

@@ -67,7 +67,7 @@
 /datum/ai_controller/basic_controller/mothroach
 	blackboard = list()
 
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 	planning_subtrees = list(

code/modules/mob/living/basic/vermin/mouse.dm

@@ -357,7 +357,7 @@
 		BB_TARGETTING_DATUM = new /datum/targetting_datum/basic(), // Use this to find people to run away from
 	)
 
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 	planning_subtrees = list(
@@ -401,7 +401,7 @@
 		BB_LOW_PRIORITY_HUNTING_TARGET = null, // cable
 	)
 
-	ai_traits = STOP_MOVING_WHEN_PULLED | STOP_ACTING_WHILE_DEAD
+	ai_traits = STOP_MOVING_WHEN_PULLED
 	ai_movement = /datum/ai_movement/basic_avoidance
 	idle_behavior = /datum/idle_behavior/idle_random_walk
 	planning_subtrees = list(