More cleanly remove LED_BUILTIN (#10179)

* Test PR to remove LED_BUILTIN 

Comment out the LED_BUILTIN definition in platformio.ini

* Add LED_BUILTIN definition to nrf52840.ini

variants/nrf52840/nrf52840.ini

@@ -4,6 +4,7 @@ extends = nrf52_base
 build_flags =
    ${nrf52_base.build_flags}
   -DSERIAL_BUFFER_SIZE=4096
+  -DLED_BUILTIN=-1
 
 lib_deps =
   ${nrf52_base.lib_deps}
@@ -79,4 +80,4 @@ debug_speed = 4000
 
 ; The following is not needed because it automatically tries do this
 ;debug_server_ready_pattern = -.*GDB server started on port \d+.*
-;debug_port = localhost:3333
+;debug_port = localhost:3333