key/server: don't log messages
key/server: don't log messages

The rpc/keyserver package is responsible for this, just as dir/server
does not log; it leaves it up to rpc/dirserver.

Change-Id: I43ddea8a95b3ce276f271e0b4526b78a46107e31
Reviewed-on: https://upspin-review.googlesource.com/16182
Reviewed-by: Eric Grosse <3706282e8b8557d7b3733fe2b8fbbcffca452208@gmail.com>

upspin/upspin,upspin/upspin