* 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
- Creates a new StackTemplateRegistry that uses the new names
- The new registry only respects stack.templates.enabled for index templates
- Renames the old registry to LegacyStackTemplateRegistry
- Component templates are not duplicated but registered under two different names
- Documents the new naming convention
- Index templates are not renamed, at least for now, as there are some challenges with it
See 7fd0423 for more details.
We are adding a _meta field to many of our REST APIs so that users can attach whatever metadata they
want. The data in this field will not be used by Elasticsearch. This commit add the _meta field to ingest
pipelines.
