No input files for tutorial available

The mentioned input files (https://github.com/key4hep/key4hep-tutorials/blob/4c03fc9f1d6a75faaf741ca419dfede247aea862/introduction_key4hep/README.md?plain=1#L32) for the introduction do not exist on the desy nfs anymore.
Trying to convert other LCIO files on `/pnfs/desy.de/` to edm4hep does not work because of a problem with `lcio2edm4hep`:
```lcio2edm4hep /pnfs/desy.de/ilc/prod/ilc/c/mc-2020/ild/dst-merged/250-SetA/higgs/ILD_l5_o2_v02/v02-02-01/00015673/000/rv02-02-01.sv02-02-01.mILD_l5_o2_v02.E250SetA.I402003.Pe2e2h.eL.pR.n000.d_dstm_15673_0.slcio $HOME/promotion/tmp/test.edm4hep.root```
Causes:
```
-01.sv02-02-01.mILD_l5_o2_v02.E250SetA.I402003.Pe2e2h.eL.pR.n000.d_dstm_15673_0.slcio $HOME/promotion/tmp/test.edm4hep.root250-SetA/higgs/ILD_l5_o2_v02/v02-02-01/00015673/000/rv02-02-
terminate called after throwing an instance of 'sio::exception'
what(): /tmp/root/spack-stage/spack-stage-lcio-d1ea9fa8964743e253da3b3960ce6f916900e2ca_develop-as25sz46u5ibh2ahafy7npzl7d3k3k3u/spack-src/src/cpp/src/MT/LCReader.cc (l.49) in open: Couldn't open input stream '/pnfs/desy.de/ilc/prod/ilc/c/mc-2020/ild/dst-merged/250-SetA/higgs/ILD_l5_o2_v02/v02-02-01/00015673/000/rv02-02-01.sv02-02-01.mILD_l5_o2_v02.E250SetA.I402003.Pe2e2h.eL.pR.n000.d_dstm_15673_0.slcio' [not_open]
Aborted (core dumped)
```

Start with introduction_key4hep/README.md at the linked line and verify whether the referenced input files are still available on the DESY NFS. Reproduce the shown lcio2edm4hep command and inspect the reported LCIO opening failure. Done means the introduction points to usable input files and its conversion step works, or clearly documents the required replacement.

Written by the indexing model from the issue text.