Fixes a bunch of callbacks that were being qdeleted, and code cleanup (#77904)

## About The Pull Request


![image](https://github.com/tgstation/tgstation/assets/13398309/559eb50a-461c-4220-b628-55412baaffc3)

Continuing the work of
https://github.com/tgstation/tgstation/pull/77850.

it started with finding one that was being missed and causing a
runtime...then I noticed a whole lot more. While I was doing this I
found callbacks that weren't being nulled in `Destroy()`, so I added
that wherever I found these spots as well as some general code cleanup.

There were a lot more of these than I initially hoped to encounter so
I'm labeling it as a refactor.

## Why It's Good For The Game

Fixes lots of runtimes, improves code resiliency.

## Changelog

🆑
refactor: fixed a bunch of instances of callbacks being qdeleted and
cleaned up related code
/🆑

code/datums/components/basic_mob_attack_telegraph.dm

@@ -25,6 +25,13 @@
 	src.telegraph_duration = telegraph_duration
 	src.on_began_forecast = on_began_forecast
 
+/datum/component/basic_mob_attack_telegraph/Destroy(force, silent)
+	if(current_target)
+		forget_target(current_target)
+	target_overlay = null
+	on_began_forecast = null
+	return ..()
+
 /datum/component/basic_mob_attack_telegraph/RegisterWithParent()
 	. = ..()
 	RegisterSignal(parent, COMSIG_HOSTILE_PRE_ATTACKINGTARGET, PROC_REF(on_attack))