[lldb] Fix broken pipe error (#127100)
During LLDB testing on slow machines with the remote-linux platform all
tests from llgs category fail with python exception `BrokenPipeError`.
The main reason of these failures is slow start of lldb-server in
gdbserver mode. Due to this desired gdbserver socket does not have time
to open by the time the Python script tries to establish a connection.
List of failed tests:
```
TestAppleSimulatorOSType.py
TestGdbRemoteAttach.py
TestGdbRemoteAuxvSupport.py
TestGdbRemoteCompletion.py
TestGdbRemoteExitCode.py
TestGdbRemoteExpeditedRegisters.py
TestGdbRemoteHostInfo.py
TestGdbRemoteKill.py
TestGdbRemoteLaunch.py
TestGdbRemoteModuleInfo.py
TestGdbRemotePlatformFile.py
TestGdbRemoteProcessInfo.py
TestGdbRemoteRegisterState.py
TestGdbRemoteSaveCore.py
TestGdbRemoteSingleStep.py
TestGdbRemoteThreadsInStopReply.py
TestGdbRemote_qThreadStopInfo.py
TestGdbRemote_vCont.py
TestLldbGdbServer.py
TestNonStop.py
TestPtyServer.py
TestGdbRemoteAttachWait.py
TestGdbRemoteConnection.py
TestStubSetSID.py
TestGdbRemoteAbort.py
TestGdbRemoteSegFault.py
TestGdbRemoteLibrariesSvr4Support.py
TestGdbRemoteMemoryAllocation.py
TestGdbRemoteMemoryTagging.py
TestGdbRemoteGPacket.py
TestGdbRemoteTargetXmlPacket.py
TestGdbRemote_QPassSignals.py
TestGdbRemoteThreadName.py
TestPartialResume.py
TestSignal.py
```
This patch implements an additional check for the opened socket on
lldb-server side and fixes this error.
