Cleans up defib code a little (#5507)

# About the pull request
removes the "heart_already_damaged" var from the defib file, instead
just having the defib check if it failed before applying the random
chance for heart damage
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# Explain why it's good for the game

![image](https://github.com/cmss13-devs/cmss13/assets/54422837/631fe43d-d77a-4d3c-b3ff-1a422298dd50)
# Testing Photographs and Procedure
<details>
<summary>Test here</summary>


https://github.com/cmss13-devs/cmss13/assets/54422837/cd5753fb-0909-4957-8867-a06a093eaacc


Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog
no player facing changes

code/game/objects/items/devices/defibrillator.dm

@@ -194,11 +194,6 @@
 	shock_cooldown = world.time + 10 //1 second cooldown before you can shock again
 
 	var/datum/internal_organ/heart/heart = H.internal_organs_by_name["heart"]
-	/// Has the defib already caused the chance of heart damage, to not potentially double up later
-	var/heart_already_damaged = FALSE
-	if(heart && prob(25))
-		heart.take_damage(rand(min_heart_damage_dealt, max_heart_damage_dealt), TRUE) // Make death and revival leave lasting consequences
-		heart_already_damaged = TRUE
 
 	if(!H.is_revivable())
 		playsound(get_turf(src), 'sound/items/defib_failed.ogg', 25, 0)
@@ -236,7 +231,7 @@
 		user.track_life_saved(user.job)
 		user.life_revives_total++
 		H.handle_revive()
-		if(heart && !heart_already_damaged)
+		if(heart)
 			heart.take_damage(rand(min_heart_damage_dealt, max_heart_damage_dealt), TRUE) // Make death and revival leave lasting consequences
 
 		to_chat(H, SPAN_NOTICE("You suddenly feel a spark and your consciousness returns, dragging you back to the mortal plane."))
@@ -245,6 +240,8 @@
 	else
 		user.visible_message(SPAN_WARNING("[icon2html(src, viewers(src))] \The [src] buzzes: Defibrillation failed. Vital signs are too weak, repair damage and try again.")) //Freak case
 		playsound(get_turf(src), 'sound/items/defib_failed.ogg', 25, 0)
+		if(heart && prob(25))
+			heart.take_damage(rand(min_heart_damage_dealt, max_heart_damage_dealt), TRUE) // Make death and revival leave lasting consequences
 
 /obj/item/device/defibrillator/compact_adv
 	name = "advanced compact defibrillator"