Use default hdf5 file locking

[nvaytet]

See https://git.esss.dk/dmsc-nightly/dmsc-nightly/-/issues/57

The part of code that handles the lock when opening nexus files (mainly https://github.com/scipp/essreduce/blob/main/src/ess/reduce/nexus/_nexus_loader.py#L240) should be able to go away.

[YooSunYoung]

I got the error again!
https://git.esss.dk/dmsc-nightly/dmsc-nightly/-/jobs/88154#L505

[jl-wynen]

DST set HDF_USE_FILE_LOCKING=FALSE on the GL runner, VISA, and the cluster now. So we should be able to ditch our workaround. But is that better than keeping it? For one, it would require us to preserve that flag, e.g., when using tox or some other tool to manage python processes.