Gets rid of ignored_factions (#94972)

## About The Pull Request

Tin, this is redundant now that faction has been moved to the atom. Also
fixes a misc runtime that can occur if someone clicks an ashwalker egg
before team datums are created

## Why It's Good For The Game

Updates code

## Changelog

Not player-facing

code/modules/antagonists/heretic/magic/rust_wave.dm

@@ -93,7 +93,7 @@
 	damage_type = TOX
 	hitsound = 'sound/items/weapons/punch3.ogg'
 	trigger_range = 0
-	ignored_factions = list(FACTION_HERETIC)
+	faction = list(FACTION_HERETIC)
 	range = 15
 	speed = 1