Rename song constants using Japanese sound test menu

data/maps/FuchsiaCity_Gym/map.json

@@ -2,7 +2,7 @@
   "id": "MAP_FUCHSIA_CITY_GYM",
   "name": "FuchsiaCity_Gym",
   "layout": "LAYOUT_FUCHSIA_CITY_GYM",
-  "music": "BGM_FRLG_GYM",
+  "music": "MUS_GYM",
   "region_map_section": "MAPSEC_FUCHSIA_CITY",
   "requires_flash": false,
   "weather": "WEATHER_NONE",

data/maps/FuchsiaCity_Gym/text.inc

@@ -9,7 +9,7 @@ Text_19832E:: @ 819832E
     .string "Poison brings steady doom.\n"
     .string "Sleep renders foes helpless.\p"
     .string "Despair to the creeping horror of\n"
-    .string "POISON-type POKéMON!{PLAY_BGM}{BGM_FRLG_LEADER_EYE}$"
+    .string "POISON-type POKéMON!{PLAY_BGM}{MUS_EXEYE}$"
 
 Text_198444:: @ 8198444
     .string "Humph!\n"