* 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
PRs #73062 and #73043 repurposed the `alias` anchor for a new guide for index
and data stream aliases. Previously, this anchor was used for our field alias
documentation.
Repurposing the anchor has caused continuity errors for users selecting
different versions of the ES docs. It could also cause confusion for users with
a `/current/` link to the `alias` page.
This updates the anchor for the alias guide and adds a redirect page to
disambiguate the `alias` anchor.
It also fixes a bread crumb issue for redirects following the 'Modifying your
Data' redirect page.
Closes#77034.
