libhdfs++: automatic CI tests are getting stuck in test_libhdfs_mini_stress_hdfspp_test_shim_static

All of the automated tests seem to get stuck, or at least stop generating useful output, in test_libhdfs_mini_stress_hdfspp_test_shim_static. Not able to reproduce the issue locally in docker.

Right now this is blocking a few patches, and not having those patches committed is slowing down work on other parts of the library.