client: remove 30s default write timeout

The reasoning for not having the default (potentially user overrided)
timeout was weak and could make some recovery situations slow, so let's
remove it. This now gives the sasl handshake 10s by default per step.

pkg/kgo/client.go

@@ -269,13 +269,6 @@ func (c *connTimeouter) timeouts(req kmsg.Request) (r, w time.Duration) {
  case *kmsg.FetchRequest:
  return def + millis(t.MaxWaitMillis), def
 
- // SASL may interact with an external system; we give each step
- // of the read process 30s by default.
-
- case *kmsg.SASLHandshakeRequest,
- *kmsg.SASLAuthenticateRequest:
- return 30 * time.Second, def
-
  // Join and sync can take a long time. Sync has no notion of
  // timeouts, but since the flow of requests should be first
  // join, then sync, we can stash the timeout from the join.