Reduces spawn limit for Mudskipper and Kilo (#4248)

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## About The Pull Request

Mudskipper and Kilo were the only ships with a spawn limit higher than
1, and this was to help ensure smaller ships would be available for
players to spawn. Now that several small independent ships are being
added to the game, this is less of a concern. Also it might reduce the
number of solo ships clogging up the manifest, marginally.

## Why It's Good For The Game

maybe a little less soloshipping would be good for the game. you WILL
interact with other players in the multiplayer game

## Changelog

:cl:
balance: Reduced Mudskipper and Kilo spawn limit to 1 each
/:cl:

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_maps/configs/independent_kilo.json

@@ -16,6 +16,7 @@
 	"map_short_name": "Kilo-class",
 	"starting_funds": 1500,
 	"map_path": "_maps/shuttles/independent/independent_kilo.dmm",
+	"limit": 1,
 	"job_slots": {
 		"Captain": {
 			"outfit": "/datum/outfit/job/independent/captain/cheap",

_maps/configs/independent_mudskipper.json

@@ -16,7 +16,7 @@
 		"SPACE"
 	],
 	"map_path": "_maps/shuttles/independent/independent_mudskipper.dmm",
-	"limit": 2,
+	"limit": 1,
 	"starting_funds": 1500,
 	"job_slots": {
 		"Salvage Leader": {