RFR: 8326578: Clean up networking properties documentation

[Julian Waters]

On Fri, 23 Feb 2024 16:59:12 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

> Please review this patch that removes the specification of system properties that are no longer used:
> - `http.auth.digest.cnonceRepeat` system property was removed in JDK 5
> - `java.net.socks.username` and `java.net.socks.password` were never available as system properties; they were available as user preferences. The support for these preferences was removed in JDK 7.
> 
> Additionally I updated the SOCKS proxy specification to match the user guide, and added the information that SOCKS proxies are only used by java.net TCP connections; the NIO SocketChannel does not support SOCKS proxies.

Marked as reviewed by jwaters (Committer).

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PR Review: https://git.openjdk.org/jdk/pull/17988#pullrequestreview-1899224772