The -terminate-tls flag is for the tcp subsubcommand, not the serve
subcommand like the usage example suggests.
Signed-off-by: salman <salman@tailscale.com>
Nodes which have both -advertise-exit-node and -exit-node in prefs
should continue have them until the next invocation of `tailscale up`.
Updates #3569.
Signed-off-by: salman <salman@tailscale.com>