Demotes the "electrical conductivity" flag from flags_1 to obj_flags (#80033)

## About The Pull Request

Code to handle this flag only ever existed on the `/obj` sublevel, so
there's no need for it to be on the `/atom` level `flags_1`. There was
probably a point in time in which mobs or turfs conducted electricity
but there's zero code for it anymore so we truly just live in a society
now.
## Why It's Good For The Game

Frees up a slot on `flags_1` (which is really nice actually), proper
scoping of certain bitflag stuff, etc.
## Changelog
Not relevant to players.

I may have screwed something up, will be doing a few passes on this
myself to ensure all the search and replaces went alright but we should
be good™️

code/modules/mining/ores_coins.dm

@@ -298,7 +298,7 @@ GLOBAL_LIST_INIT(sand_recipes, list(\
 		attacher = key_name(user)
 		user.balloon_alert_to_viewers("attached rig")
 		return
-	
+
 	if(I.tool_behaviour == TOOL_WRENCH && rig)
 		rig.on_found()
 		if(QDELETED(src))
@@ -410,7 +410,7 @@ GLOBAL_LIST_INIT(sand_recipes, list(\
 	icon = 'icons/obj/economy.dmi'
 	name = "coin"
 	icon_state = "coin"
-	flags_1 = CONDUCT_1
+	obj_flags = CONDUCTS_ELECTRICITY
 	force = 1
 	throwforce = 2
 	w_class = WEIGHT_CLASS_TINY