Removes unused camera var (#6038)

# About the pull request

Removes a variable we don't use on cameras.

# Explain why it's good for the game

Tidier code is always nice.

# Changelog
:cl:
code: Removes an unused camera var.
/:cl:

code/game/machinery/camera/camera.dm

@@ -10,7 +10,6 @@
 
 	var/list/network = list(CAMERA_NET_MILITARY)
 	var/c_tag = null
-	var/c_tag_order = 999
 	var/status = 1
 	anchored = TRUE
 	var/panel_open = FALSE // 0 = Closed / 1 = Open