Not THAT Slow - Update Movespeed Modifiers for Smooth Movement (#22127)

The /tg/-style movespeed_modifier datums were not incorporated into the
original smooth movement PR. While
https://github.com/Aurorastation/Aurora.3/pull/22043 restores that
functionality, the original values no longer feel good now that we're on
smooth movement. This PR halves ALL movespeed_modifier/slowdown datums,
with the exception of species-native, as a baseline before more
individual adjustments are made.

code/game/objects/items/weapons/storage/backpack.dm

@@ -592,7 +592,7 @@
 	icon = 'icons/obj/storage/duffelbag.dmi'
 	icon_state = "duffel"
 	item_state = "duffel"
-	slowdown = 1
+	slowdown = 0.3
 	max_storage_space = DEFAULT_DUFFELBAG_STORAGE
 	straps = TRUE
 

code/game/objects/items/weapons/storage/bags.dm

@@ -324,7 +324,7 @@
 	storage_slots = 100
 	max_storage_space = 200
 	w_class = WEIGHT_CLASS_BULKY
-	slowdown = 1
+	slowdown = 0.5
 	can_hold = list(
 		/obj/item/reagent_containers/pill,
 		/obj/item/reagent_containers/glass/beaker,

code/game/objects/items/weapons/vaurca_items.dm

@@ -298,7 +298,7 @@
 	icon_state = "scout"
 	item_state = "scout"
 	desc = "Armor designed for K'laxan scouts, made of lightweight sturdy material that does not restrict movement."
-	slowdown = -0.2
+	slowdown = -0.1
 
 	species_restricted = list(BODYTYPE_VAURCA)
 	armor = list(