Hypospray Mk. II defaults to 5u dose (#2303)

## About The Pull Request

Makes the hypospray vials default consumption amount to 5u, aligning it
with other methods such as drinking from a bottle or beaker.

## Why It's Good For The Game

- Commonality with other reagent containers, a 5u dose of a given
reagent is the most common.
- Prevent newer medical staff from wasting their vials injecting 10u
into people constantly.
- I'm lazy and don't want to adjust all the vials every time I make a
set

## Proof Of Testing

<summary>Screenshots/Videos</summary>


![image](https://github.com/user-attachments/assets/07bffebc-aba0-4db5-b57e-babc307c23b7)

</details>

## Changelog

🆑 LT3
qol: Hypovial dosage is now 5u by default
/🆑

modular_skyrat/modules/hyposprays/code/hypovials.dm

@@ -7,6 +7,7 @@
 	fill_icon_state = "hypovial_fill"
 	spillable = FALSE
 	volume = 10
+	amount_per_transfer_from_this = 5
 	possible_transfer_amounts = list(1,2,5,10)
 	fill_icon_thresholds = list(10, 25, 50, 75, 100)
 	var/chem_color = "#FFFFFF" //Used for hypospray overlay