This may help address #7409 if the underlying cause is the deterministic
volume ID. However, not all boards have working urandom (samd21
at least does not) so a couple of fallbacks are attempted when it fails.
I verified that on a pico_w, each `storage.erase_filesystem()` gives
a distinct 32-bit volume ID (pico_w's urandom can never fail)
Scott Shawcroft
Jeff Epler
Damien George