node: add log message when boot is aborted

[holiman]

This PR adds a diagnostic log message to figure out why #20642 doesn't work.

[user@work go-ethereum]$ ./build/bin/geth --rpc --rpcapi foo,baz
...
ERROR[02-13|10:33:47.837] Failed to enumerate USB devices          hub=trezor vendor=4617  failcount=3 err="failed to initialize libusb: libusb: unknown error [code -99]"
ERROR[02-13|10:33:47.837] Failed to enumerate USB devices          hub=trezor vendor=21324 failcount=3 err="failed to initialize libusb: libusb: unknown error [code -99]"
ERROR[02-13|10:33:49.237] Aborting startup                         error="invalid API \"foo\" in whitelist (available: admin, debug, web3, eth, txpool, personal, ethash, miner, net)"

[fjl]

Closing in favor of #20684