Increase the number of vector dims to 2048

[mayya-sharipova]

No description provided.

[elasticmachine]

Pinging @elastic/es-search

[mayya-sharipova]

As there are some neural networks that produce vectors with dims > 1024 (see a discussion here, we need to increase the max dims to 2048.

[mayya-sharipova]

For 7.5 backport a note with increased number of dims will be added to migrate_7_5.asciidoc.

[mayya-sharipova]

@jtibshirani This PR is ready for another review.

[mayya-sharipova]

@elasticmachine run elasticsearch-ci/1

[mayya-sharipova]

@elasticmachine run elasticsearch-ci/docs-check

[mayya-sharipova]

@elasticmachine run elasticsearch-ci/oss-distro-docs

[jtibshirani]

Looks good to me.

[jtibshirani]

For future context, we made the decision to raise the limit because we've encountered a couple well-known models that produce vectors with > 1024 dimensions.

We're not planning to increase the limit further unless we hear from a few users about common models/ use cases that require more dimensions.