log: Remove "No rpcpassword set" from logs
log: Remove "No rpcpassword set" from logs

Summary:
> rpcpassword is deprecated and not recommended anymore. So remove it from the logs, which indicate that an rpcpassword should be set and cause confusion.

This is a backport of Core [[https://github.com/bitcoin/bitcoin/pull/18999 | PR18999]]

Test Plan: src/bitcoind -regtest -printtoconsole | grep cookie

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D9137

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