Remove self-extinguishing with acid spray (#6508)

# About the pull request
This PR makes it so you cannot extinguish yourself with your own spray
(this includes things that used to be possible like starting acid spray
with base praetorian and dashing to the end or extinguishing yourself
with spitter and bonus movement speed)
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# Explain why it's good for the game
Self-extinguishing discourages teamwork and makes castes that are
supposed to be vulnerable to fire able to wipe it off easily.
# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

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

</details>


# Changelog
:cl:
balance: You can no longer extinguish yourself with your own acid spray.
/:cl:

---------

Co-authored-by: Drathek <[email protected]>

code/game/objects/effects/aliens.dm

@@ -106,14 +106,16 @@
 		// Humans?
 		if(isliving(atm)) //For extinguishing mobs on fire
 			var/mob/living/M = atm
-			M.ExtinguishMob()
+
+			if(M != cause_data.resolve_mob())
+				M.ExtinguishMob()
+
 			if(M.stat == DEAD) // NO. DAMAGING. DEAD. MOBS.
 				continue
 			if (iscarbon(M))
 				var/mob/living/carbon/C = M
 				if (C.ally_of_hivenumber(hivenumber))
 					continue
-
 				apply_spray(M)
 				M.apply_armoured_damage(get_xeno_damage_acid(M, damage_amount), ARMOR_BIO, BURN) // Deal extra damage when first placing ourselves down.
 
@@ -144,6 +146,9 @@
 
 /obj/effect/xenomorph/spray/Crossed(AM as mob|obj)
 	..()
+	if(AM == cause_data.resolve_mob())
+		return
+
 	if(isliving(AM))
 		var/mob/living/living_mob = AM
 		if(living_mob.ally_of_hivenumber(hivenumber))