* Remove `es-test-dir` book-scoped variable
* Remove `plugins-examples-dir` book-scoped variable
* Remove `:dependencies-dir:` and `:xes-repo-dir:` book-scoped variables
- In `index.asciidoc`, two variables (`:dependencies-dir:` and `:xes-repo-dir:`) were removed.
- In `sql/index.asciidoc`, the `:sql-tests:` path was updated to fuller path
- In `esql/index.asciidoc`, the `:esql-tests:` path was updated idem
* Replace `es-repo-dir` with `es-ref-dir`
* Move `:include-xpack: true` to few files that use it, remove from index.asciidoc
This change adds support for kNN vector fields to the `_disk_usage` API. The
strategy:
* Iterate the vector values (using the same strategy as for doc values) to
estimate the vector data size
* Run some random vector searches to estimate the vector index size
Co-authored-by: Yannick Welsch <yannick@welsch.lu>
Closes#84801
