When the operator enables metrics on a proxy, it uses the port 9001,
and in the near future it will start using 9002 for the debug endpoint
as well. Make sure we don't choose ports from a range that includes
9001 so that we never clash. Setting TS_SOCKS5_SERVER, TS_HEALTHCHECK_ADDR_PORT,
TS_OUTBOUND_HTTP_PROXY_LISTEN, and PORT could also open arbitrary ports,
so we will need to document that users should not choose ports from the
10000-11000 range for those settings.
Updates #13406
Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>
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