Update LittleFS Platformio example (#9151)

* rm not anymore needed `LittleFS Builder.py`

* use custom partition scheme

to guarantee a big enough SPIFFS partition scheme is used.

libraries/LittleFS/examples/LITTLEFS_PlatformIO/littlefsbuilder.py

-Import("env")
-env.Replace( MKFSTOOL=env.get("PROJECT_DIR") + '/mklittlefs' )  # PlatformIO now believes it has actually created a SPIFFS

libraries/LittleFS/examples/LITTLEFS_PlatformIO/platformio.ini

@@ -17,8 +17,6 @@ framework = arduino
 [env:esp32]
 platform = espressif32
 board = esp32dev
-;board_build.partitions = partitions_custom.csv
+board_build.partitions = partitions_custom.csv
 monitor_filters = esp32_exception_decoder
 monitor_speed = 115200
-
-extra_scripts = ./littlefsbuilder.py