cli/flags: hide --advrertise-sql-addr from the output of --help

[knz]

See discussion in #52266.

Release note: None

[cockroach-teamcity]

This change is 

[knz]

@bdarnell reviewed this PR in #52266 :

As for hiding it from --help in the meantime, I'm not a fan of hidden options unless the support burden is really high. This one is straightforward enough - if you're using both --sql-addr and --advertise-addr, you should probably also use --sql-advertise-addr, and set it using the same logic you used for --advertise-addr.

Closing this PR in favor of clarification in docs.