Default storage size for RP2350 on-board flash

[oyama]

Determine a reasonable value for the size of onboard flash storage allocated by default in pico-vfs.

Currently, 1408 * 1024 bytes is used, following MicroPython's PR2040 definition.
For hardware with different flash storage sizes, such as Pico 2, how would it be appropriate to determine the consumption of the default on-board flash storage size?

MicroPython sets the storage size individually depending on the hardware - the Pico 2 uses (PICO_FLASH_SIZE_BYTES - 1024 * 1024).