Consolidate index version checks

[jtibshirani]

In order maintain compatibility with older indices, we sometimes need to check the index version and take special action. These index version checks happen in a variety of places and ways, making it hard to understand what logic depends on the index version. It also means that compatibility logic is scattered throughout various components, which hurts code quality.

It would be good to consolidate index version checks as much as possible. Some ideas:

• Reduce ways of checking the index version setting, ideally to one. Reduce ways of checking index version setting. #65396
• Consolidate version checking logic into a small number of components, like MapperService.
  • Remove unnecessary references to index version. Remove unnecessary references to index version. #65402, Remove IndicesService#isMetadataField. #65782, Avoid passing Lucene version to Store#createEmpty. #65783, Remove unused method IndexShard#minimumCompatibleVersion. #65866
• Stop exposing the index version broadly through index settings (?)

[elasticmachine]

Pinging @elastic/es-search (Team:Search)

[elasticmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[icemakegirl]

I have a question, is this issue still open? apparently all the quest are done
I am a beginner Dev

[javanna]

I think we can close this, what do you think @rjernst ?

[rjernst]

I agree, this can be closed. We now have IndexVersion which mostly satisfies the consolidation originally envisioned.