**Build scan:**
https://gradle-enterprise.elastic.co/s/w5uoitwbjlubk/tests/:server:test/org.elasticsearch.transport.RemoteClusterConnectionTests/testCloseWhileConcurrentlyConnecting

**Reproduction line:**
```
./gradlew ':server:test' --tests "org.elasticsearch.transport.RemoteClusterConnectionTests.testCloseWhileConcurrentlyConnecting" -Dtests.seed=1D1BC140B0F8A67C -Dtests.locale=sk -Dtests.timezone=Africa/Blantyre -Druntime.java=20
```

**Applicable branches:**
main

**Reproduces locally?:**
No

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.transport.RemoteClusterConnectionTests&tests.test=testCloseWhileConcurrentlyConnecting

**Failure excerpt:**
```
com.carrotsearch.randomizedtesting.UncaughtExceptionError: Captured an uncaught exception in thread: Thread[id=1746, name=Thread-113, state=RUNNABLE, group=TGRP-RemoteClusterConnectionTests]


  Caused by: java.lang.AssertionError: cluster:internal/remote_cluster/handshake

    at __randomizedtesting.SeedInfo.seed([1D1BC140B0F8A67C]:0)
    at org.elasticsearch.transport.InboundAggregator.lambda$new$0(InboundAggregator.java:46)
    at org.elasticsearch.transport.InboundAggregator.initializeRequestState(InboundAggregator.java:197)
    at org.elasticsearch.transport.InboundAggregator.headerReceived(InboundAggregator.java:66)
    at org.elasticsearch.transport.InboundPipeline.forwardFragments(InboundPipeline.java:138)
    at org.elasticsearch.transport.InboundPipeline.doHandleBytes(InboundPipeline.java:121)
    at org.elasticsearch.transport.InboundPipeline.handleBytes(InboundPipeline.java:86)
    at org.elasticsearch.transport.netty4.Netty4MessageInboundHandler.channelRead(Netty4MessageInboundHandler.java:63)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
    at io.netty.handler.logging.LoggingHandler.channelRead(LoggingHandler.java:280)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
    at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
    at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:689)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:652)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562)
    at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    at java.lang.Thread.run(Thread.java:1623)

```
server/src/test/java/org/elasticsearch/transport/RemoteClusterConnectionTests.java
try (Socket accept = socket.accept()) {
                        acceptedLatch.countDown();
                        closeRemote.await();
                    } catch (IOException e) {
                        
                    } catch (InterruptedException e) {
                        Thread.currentThread().interrupt();
                    }
                }
            };
            t.start();
            try (
                MockTransportService service = MockTransportService.createNewService(
                    Settings.EMPTY,
                    Version.CURRENT,
                    TransportVersion.CURRENT,
                    threadPool,
                    null
                )
            ) {
                service.start();
                service.acceptIncomingRequests();
                CountDownLatch listenerCalled = new CountDownLatch(1);
                AtomicReference<Exception> exceptionReference = new AtomicReference<>();
                String clusterAlias = "test-cluster";
                Settings settings = buildRandomSettings(clusterAlias, addresses(seedNode));
                try (RemoteClusterConnection connection = new RemoteClusterConnection(settings, clusterAlias, service, randomBoolean())) {
                    ActionListener<Void> listener = ActionListener.wrap(x -> {
                        listenerCalled.countDown();
                        fail("expected exception");