Adds Effects to the Death of Customer Robots and Mech Wreckages (#94391)

## About The Pull Request

A first, small change so that robot customers and mech wreckages produce
robot debris upon being killed/destroyed, rather than simply deleting
themselves. Customers, in specific, will undergo a similar gibbing
process as real borgs: sparking and scattering robot debris without the
animation. Wreckages, instead, will make a large noise, shake the camera
of close people, and collapse into a single robot debris (as it was
already mostly destroyed by this point).

## Why It's Good For The Game

The destruction of these two entities is otherwise underwhelming when
they disappear into the aether with little fanfare. Also provides the
chef and janitor with another thing to get mad about when John Assistant
throws sharp sticks at the kitchen's customers.

## Changelog
🆑
add: Robot customers and mech wreckage destruction are messier. Bring a
mop!
/🆑

---------

Co-authored-by: san7890 <the@san7890.com>

code/modules/mob/living/basic/space_fauna/robot_customer.dm

@@ -118,3 +118,8 @@
 		order = attending_venue.order_food_line(wanted_item)
 
 	. += span_notice("Their order was: \"[order].\"")
+
+/mob/living/basic/robot_customer/death()
+	new /obj/effect/gibspawner/robot(drop_location())
+
+	return ..()