Changed auto generated index name

[shubhamsrkdev]

The auto generated index name though informative is very long leading to errors like:

Could not start recording, not able to write to file /local/home/username/lucenebenchy/logs/baseline_vs_patch/2026.01.06.11.14.39/bench-index-baseline_vs_patch-wikimediumall.lucene_candidate.c
andidate.facets.taxonomy:Date.taxonomy:Month.taxonomy:DayOfYear.sortedset:Date.sortedset:Month.sortedset:DayOfYear.taxonomy:RandomLabel.sortedset:RandomLabel.Lucene90.Lucene104.dvfields.nd33.3326M.jfr. /local/home/username/lucenebenchy/logs/baseline_vs_patch/2026.01.06.11.14.39/bench-index-baseline_vs_patch-wikimediumall.lucene_candidate.candidate.facets.taxonomy:Date.taxonomy:Month.taxonomy:DayOfYear.sortedset:Date.sortedset:Month.sorted
set:DayOfYear.taxonomy:RandomLabel.sortedset:RandomLabel.Lucene90.Lucene104.dvfields.nd33.3326M.jfr: File name too long 
Error occurred during initialization of VM

This PR reduces the file name size and also added a metadata file to verify if the index is not reduced.

Fixes #198

[mikemccand]

Thank you for tackling this! It is super annoying when it strikes!

As a short-term workaround, you can tell your local Competition (or Index instance maybe) which index name you want to use, overriding this overly-verbose default.

[mikemccand]

Looks like you need a make tidy maybe? Or possibly make ruff-fix?

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