[HealthCheck] Make status logging better

src/core/load_balancing/pick_first/pick_first.cc

@@ -648,7 +648,8 @@ void PickFirst::HealthWatcher::OnConnectivityStateChange(
     case GRPC_CHANNEL_TRANSIENT_FAILURE:
       policy_->channel_control_helper()->UpdateState(
           GRPC_CHANNEL_TRANSIENT_FAILURE, status,
-          MakeRefCounted<TransientFailurePicker>(status));
+          MakeRefCounted<TransientFailurePicker>(absl::UnavailableError(
+              absl::StrCat("health watch: ", status.message()))));
       break;
     case GRPC_CHANNEL_SHUTDOWN:
       Crash("health watcher reported state SHUTDOWN");
@@ -1644,9 +1645,9 @@ void OldPickFirst::SubchannelList::SubchannelData::OnConnectivityStateChange(
     // If there is a pending update, switch to the pending update.
     if (p->latest_pending_subchannel_list_ != nullptr) {
       GRPC_TRACE_LOG(pick_first, INFO)
-          << "Pick First " << p << " promoting pending subchannel "
-          << "list " << p->latest_pending_subchannel_list_.get()
-          << " to replace " << p->subchannel_list_.get();
+          << "Pick First " << p << " promoting pending subchannel list "
+          << p->latest_pending_subchannel_list_.get() << " to replace "
+          << p->subchannel_list_.get();
       p->UnsetSelectedSubchannel();
       p->subchannel_list_ = std::move(p->latest_pending_subchannel_list_);
       // Set our state to that of the pending subchannel list.