Fix SA-8 LD used incorrectly as SA-13 and cleanup

- The SA-8 LD unit hat the SA-13 unit name as variant. The Layout tried to create a SA-13 SHORAD Site but actually used an SA-8 LD unit instead with zero threat range. This resulted in a yellow marked GroundObject on the map
- Cleaned up the treat and radar range functions a bit

resources/units/ground_units/SA-8 Osa LD 9T217.yaml

@@ -1,4 +1,4 @@
-class: SHORAD
+class: Logistics
 description: "The 9K33 Osa (Russian: 9\u041A33 \xAB\u041E\u0441\u0430\xBB, literally\
   \ \"wasp\"; NATO reporting name SA-8 Gecko) is a highly mobile, low-altitude, short-range\
   \ tactical surface-to-air missile system developed in the Soviet Union in the 1960s\
@@ -6,7 +6,7 @@ description: "The 9K33 Osa (Russian: 9\u041A33 \xAB\u041E\u0441\u0430\xBB, liter
 introduced: 1981
 manufacturer: Ulyanovsk
 origin: USSR/Russia
-price: 22
+price: 3
 role: Self-Propelled Surface-to-Air Missile Launcher
 variants:
-  SA-13 Gopher (9K35 Strela-10M3): {}
+  SAM SA-8 Osa LD 9T217: {}