AP_Scripting: increase default heap size in SITL and on F7/H7

if we have 500k or more memory then use 100k heap for Lua, making
setup easier

libraries/AP_Scripting/AP_Scripting.cpp

@@ -33,8 +33,8 @@
 #endif // !defined(SCRIPTING_STACK_MAX_SIZE)
 
 #if !defined(SCRIPTING_HEAP_SIZE)
-  #if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX
-    #define SCRIPTING_HEAP_SIZE (64 * 1024)
+  #if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX || HAL_MEM_CLASS >= HAL_MEM_CLASS_500
+    #define SCRIPTING_HEAP_SIZE (100 * 1024)
   #else
     #define SCRIPTING_HEAP_SIZE (43 * 1024)
   #endif