"io.grpc.StatusRuntimeException: UNKNOWN: channel closed" on network disconnect

### What version of gRPC-Java are you using?

1.44.0

### What is your environment?

Ubuntu 22.04

### What did you expect to see?

An UNAVAILABLE status code or something similar

### What did you see instead?

We saw things fail with this exception and stacktrace:
```
io.grpc.StatusRuntimeException: UNKNOWN: channel closed
at io.grpc.Status.asRuntimeException(Status.java:535)
at io.grpc.stub.ClientCalls$StreamObserverToCallListenerAdapter.onClose(ClientCalls.java:479)
at io.opentelemetry.instrumentation.grpc.v1_6.TracingClientInterceptor$TracingClientCall$TracingClientCallListener.onClose(TracingClientInterceptor.java:161)
at io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:562)
at io.grpc.internal.ClientCallImpl.access$300(ClientCallImpl.java:70)
at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInternal(ClientCallImpl.java:743)
at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:722)
at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133)
at com.daml.executors.QueueAwareExecutorService$TrackingRunnable.run(QueueAwareExecutorService.scala:98)
at com.daml.metrics.InstrumentedExecutorServiceMetrics$InstrumentedExecutorService$InstrumentedRunnable.run(InstrumentedExecutorServiceMetrics.scala:202)
at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1426)
at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)
Caused by: java.nio.channels.ClosedChannelException: null
at io.grpc.netty.Utils.statusFromThrowable(Utils.java:271)
at io.grpc.netty.NettyClientHandler.onConnectionError(NettyClientHandler.java:500)
at io.netty.handler.codec.http2.Http2ConnectionHandler.onError(Http2ConnectionHandler.java:641)
at io.netty.handler.codec.http2.DefaultHttp2ConnectionEncoder.writeHeaders0(DefaultHttp2ConnectionEncoder.java:251)
at io.netty.handler.codec.http2.DefaultHttp2ConnectionEncoder.writeHeaders(DefaultHttp2ConnectionEncoder.java:167)
at io.netty.handler.codec.http2.DecoratingHttp2FrameWriter.writeHeaders(DecoratingHttp2FrameWriter.java:53)
at io.netty.handler.codec.http2.StreamBufferingEncoder.writeHeaders(StreamBufferingEncoder.java:170)
at io.netty.handler.codec.http2.StreamBufferingEncoder.writeHeaders(StreamBufferingEncoder.java:158)
at io.grpc.netty.NettyClientHandler.createStreamTraced(NettyClientHandler.java:609)
at io.grpc.netty.NettyClientHandler.createStream(NettyClientHandler.java:592)
at io.grpc.netty.NettyClientHandler.write(NettyClientHandler.java:326)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:881)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:863)
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:968)
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:856)
at io.netty.channel.DefaultChannelPipeline.write(DefaultChannelPipeline.java:1015)
at io.netty.channel.AbstractChannel.write(AbstractChannel.java:301)
at io.grpc.netty.WriteQueue$AbstractQueuedCommand.run(WriteQueue.java:213)
at io.grpc.netty.WriteQueue.flush(WriteQueue.java:128)
at io.grpc.netty.WriteQueue.access$000(WriteQueue.java:34)
at io.grpc.netty.WriteQueue$1.run(WriteQueue.java:46)
at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:174)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:167)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:470)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:566)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: io.netty.channel.StacklessClosedChannelException: null
at io.netty.channel.AbstractChannel$AbstractUnsafe.write(Object, ChannelPromise)(Unknown Source)
```

Interestingly, it does look like the channel recovered from this after the connection established again.

### Steps to reproduce the bug

In our test setup, we kill the connection with toxiproxy and then see this failure but only relatively rarely. I don't have a reliable reproduce unfortunately (nor one that I can make public).

Is that expected? Given that it recovers should we just retry on `UNKNOWN: channel closed` like we do on an UNAVAILABLE?