doc: Remove outdated description for --port argument #30014

Removing an outdated sentence in the argument description for the --port argument. The note says to wait until changes in #23542 have become widespread, which I think has happened since those changes were merged over two years ago on March 2, 2022

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_{Debug: https://github.com/bitcoin/bitcoin/runs/24468747357}

Does anyone have concrete statistics on this? Or even anecdotes? i would imagine nodes on non-standard ports still get significantly fewer connections, if not the least because the DNS seeds don't support them.

It may yet be early to do this. I mentioned this change in https://jonatack.github.io/articles/using-alternative-p2p-networks-with-bitcoin-core#bitcoin-core-listening-port but have no statistics on the use of non-8333 ports for running bitcoind.

This is a duplicate of #29994.