* 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 adds troubleshooting documentation for the case when the ShardsAvailabilityHealthIndicatorService
reports that there are not enough nodes in the data tier (user action "increase_node_capacity_for_allocations" or
"increase_tier_capacity_for_allocations_". This covers both the cloud and self-managed environments. For
cloud we first recommend increasing the number of availability zones (because you cannot directly add nodes), and
decreasing index.number_of_replicas if that is not possible. For self-managed, we first recommend adding nodes,
and decreasing index.number_of_replicas if that is not possible.
This adds a troubleshooting doc for indices that mix index filtering allocation
with data tiers routing.
Co-authored-by: Lee Hinman <dakrone@users.noreply.github.com>