Forward port release notes for v8.17.9 (#131719)

* Forward port release notes for v8.17.9

* Update release-notes.asciidoc

* Update highlights.asciidoc

---------

Co-authored-by: elasticsearchmachine <infra-root+elasticsearchmachine@elastic.co>
Co-authored-by: Charlotte Hoblik <116336412+charlotte-hoblik@users.noreply.github.com>

docs/reference/release-notes.asciidoc

@@ -11,6 +11,7 @@ This section summarizes the changes in each release.
 * <<release-notes-8.18.2>>
 * <<release-notes-8.18.1>>
 * <<release-notes-8.18.0>>
+* <<release-notes-8.17.9>>
 * <<release-notes-8.17.8>>
 * <<release-notes-8.17.7>>
 * <<release-notes-8.17.6>>
@@ -101,6 +102,7 @@ include::release-notes/8.18.3.asciidoc[]
 include::release-notes/8.18.2.asciidoc[]
 include::release-notes/8.18.1.asciidoc[]
 include::release-notes/8.18.0.asciidoc[]
+include::release-notes/8.17.9.asciidoc[]
 include::release-notes/8.17.8.asciidoc[]
 include::release-notes/8.17.7.asciidoc[]
 include::release-notes/8.17.6.asciidoc[]

docs/reference/release-notes/8.17.9.asciidoc

@@ -0,0 +1,28 @@
+[[release-notes-8.17.9]]
+== {es} version 8.17.9
+
+Also see <<breaking-changes-8.17,Breaking changes in 8.17>>.
+
+[[bug-8.17.9]]
+[float]
+=== Bug fixes
+
+Aggregations::
+* Aggs: Add cancellation checks to `FilterByFilter` aggregator {es-pull}130452[#130452]
+
+ES|QL::
+* Avoid O(N^2) in VALUES with ordinals grouping {es-pull}130576[#130576]
+* Avoid dropping aggregate groupings in local plans {es-pull}129370[#129370] (issues: {es-issue}129811[#129811], {es-issue}128054[#128054])
+* Fix `BytesRef2BlockHash` {es-pull}130705[#130705]
+
+Search::
+* Fix msearch request parsing when index expression is null {es-pull}130776[#130776] (issue: {es-issue}129631[#129631])
+
+[[upgrade-8.17.9]]
+[float]
+=== Upgrades
+
+Packaging::
+* Update default docker base image to Ubuntu 24.04 {es-pull}130277[#130277]
+
+

docs/reference/release-notes/highlights.asciidoc

@@ -139,6 +139,23 @@ POST _query
 
 {es-pull}129555[#129555]
 
+[discrete]
+[[es_ql_cross_cluster_querying_generally_available]]
+=== ES|QL cross-cluster querying is now generally available
+The ES|QL Cross-Cluster querying feature has been in technical preview since 8.13.
+As of releases 8.19.0 and 9.1.0 this is now generally available.
+This feature allows you to run ES|QL queries across multiple clusters.
+
+{es-pull}130034[#130034]
+
+[discrete]
+[[mark_token_pruning_for_sparse_vector_as_ga]]
+=== Mark Token Pruning for Sparse Vector as GA
+Token pruning for sparse_vector queries has been live since 8.13 as tech preview.
+As of 8.19.0 and 9.1.0, this is now generally available.
+
+{es-pull}130212[#130212]
+
 // end::notable-highlights[]