Radiation refactor (#22158)

# Summary

This PR refactors radiation values and cleans up custom radiation values
without a definition.
This also fixes #22155.

## Changes

- Update ARMOR_RAD_STRONG 75 -> 70, now fits RAD_LEVEL_VERY_HIGH.
- Update radiation level defines:
  - NONE         = 0
  - VERY_LOW     = 1 (old LOW)
  - LOW          = 10
  - MODERATE     = 25
  - HIGH         = 40
  - VERY_HIGH    = 70 (old value was 100)
  - EXTREME      = 100
  - CATASTROPHIC = 120
- Update a couple of rad values to their respective define name (with
minor implicit balancing).
- Remove the super awkward/LRP hairloss with high radiation exposure.

code/modules/materials/materials.dm

@@ -281,7 +281,7 @@
 /material/uranium
 	name = MATERIAL_URANIUM
 	stack_type = /obj/item/stack/material/uranium
-	radioactivity = 12
+	radioactivity = RAD_LEVEL_LOW
 	icon_base = "stone"
 	reinf_icon = "reinf_stone"
 	icon_colour = "#007A00"
@@ -378,7 +378,7 @@
 /material/phoron/supermatter
 	name = MATERIAL_SUPERMATTER
 	icon_colour = "#ffff00"
-	radioactivity = 20
+	radioactivity = RAD_LEVEL_MODERATE
 	conductivity = 100
 	integrity = 10
 	luminescence = 3