Don't leak parent file descriptors to child processes

It is unexpected for the child process to inherit parent file descriptors.
Requires Qt >= 6.6 and only affects Linux.

Closes #10312.
PR #22457.

src/app/application.cpp

@@ -674,6 +674,9 @@ void Application::runExternalProgram(const QString &programTemplate, const BitTo
     QProcess proc;
     proc.setProgram(command);
     proc.setArguments(args);
+#if defined(Q_OS_UNIX) && (QT_VERSION >= QT_VERSION_CHECK(6, 6, 0))
+    proc.setUnixProcessParameters(QProcess::UnixProcessFlag::CloseFileDescriptors);
+#endif
 
     if (proc.startDetached())
     {