Fixes monkey orbiting breaking the camera (#5383)

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# About the pull request

Fixes orbiting a monkey/farwa/stok/etc. locking your camera onto it.

This was happening due to `RegisterSignal(src, COMSIG_MOVABLE_MOVED,
PROC_REF(observer_move_react))` not being called if the target mob
didn't have a HUD, meaning that the client's `eye` wouldn't be set back
to their body when they tried moving away.
I also moved the `COMSIG_PARENT_QDELETING` one over too so that the same
doesn't happen if the target mob is deleted.

(The other signals all seem to be HUD related.)

# Explain why it's good for the game

Bug!

# Testing Photographs and Procedure
<!-- Include any screenshots/videos/debugging steps of the modified code
functioning successfully, ideally including edge cases. -->
<details>
<summary>Screenshots & Videos</summary>

## Before:


https://github.com/cmss13-devs/cmss13/assets/57483089/c188db1f-4fb2-4634-baeb-b87ab6e17ae8


https://github.com/cmss13-devs/cmss13/assets/57483089/05348463-49ed-442c-80c3-9c880b4f3d91

## After:


https://github.com/cmss13-devs/cmss13/assets/57483089/3f0c8da7-d688-4523-8f63-9f743e699326


https://github.com/cmss13-devs/cmss13/assets/57483089/b39eefa3-3138-437b-bffe-89813ee0a46b

</details>


# Changelog

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:cl:
fix: Fixed observing a monkey/farwa/stok/etc. locking the camera onto
it.
/:cl:

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code/modules/mob/dead/observer/observer.dm

@@ -262,6 +262,9 @@
 	var/mob/living/carbon/human/human_target = target
 
 	client.eye = human_target
+	observe_target_mob = human_target
+	RegisterSignal(observe_target_mob, COMSIG_PARENT_QDELETING, PROC_REF(clean_observe_target))
+	RegisterSignal(src, COMSIG_MOVABLE_MOVED, PROC_REF(observer_move_react))
 
 	if(!human_target.hud_used)
 		return
@@ -290,19 +293,14 @@
 
 		break
 
-	observe_target_mob = human_target
-	RegisterSignal(observe_target_mob, COMSIG_PARENT_QDELETING, PROC_REF(clean_observe_target))
 	RegisterSignal(observe_target_mob, COMSIG_MOB_GHOSTIZE, PROC_REF(observe_target_ghosting))
 	RegisterSignal(observe_target_mob, COMSIG_MOB_NEW_MIND, PROC_REF(observe_target_new_mind))
 	RegisterSignal(observe_target_mob, COMSIG_MOB_LOGIN, PROC_REF(observe_target_login))
 
-	RegisterSignal(src, COMSIG_MOVABLE_MOVED, PROC_REF(observer_move_react))
-
 	if(human_target.client)
 		observe_target_client = human_target.client
 		RegisterSignal(observe_target_client, COMSIG_CLIENT_SCREEN_ADD, PROC_REF(observe_target_screen_add))
 		RegisterSignal(observe_target_client, COMSIG_CLIENT_SCREEN_REMOVE, PROC_REF(observe_target_screen_remove))
-		return
 
 /mob/dead/observer/reset_perspective(atom/A)
 	if(observe_target_mob)