Update CHANGELOG.md for 12.9.0

[ci skip]

changelogs/unreleased/ak-fix-multi-pod.yml

----
-title: Fix access to logs when multiple pods exist
-merge_request: 27008
-author:
-type: fixed

changelogs/unreleased/ak-move-logs-to-core.yml

----
-title: Move pod logs to core
-merge_request: 25455
-author:
-type: changed

changelogs/unreleased/ak-rescue-error.yml

----
-title: Rescue elasticsearch server error in pod logs
-merge_request: 25367
-author:
-type: fixed

changelogs/unreleased/ak-upgrade-es.yml

----
-title: Upgrade Elastic Stack helm chart to 1.9.0
-merge_request: 27011
-author:
-type: changed

changelogs/unreleased/al-205505-fix-snippet-blob-viewers.yml

----
-title: Fix snippet blob viewers for rich and plain data
-merge_request: 25945
-author:
-type: fixed

changelogs/unreleased/allow-selecting-all-queues-with-sidekiq-cluster.yml

----
-title: Allow selecting all queues with sidekiq-cluster
-merge_request: 26594
-author:
-type: added

changelogs/unreleased/allow-to-disable-defaults.yml

----
-title: Allow to disable inheritance of default job settings
-merge_request: 25690
-author:
-type: added

changelogs/unreleased/allow_toggle_modsecurity_settings.yml

----
-title: Allow enabling/disabling modsecurity from UI
-merge_request: 24747
-author:
-type: added

changelogs/unreleased/auto-deploy-image-v0-12-0.yml

----
-title: Bump Auto Deploy image to v0.12.1
-merge_request: 26336
-author:
-type: changed

changelogs/unreleased/broaden-access-scope-for-version-api.yml

----
-title: Allow access to /version API endpoint with read_user scope
-merge_request: 25211
-author:
-type: changed

changelogs/unreleased/bvl-validate-changed-values.yml

----
-title: Fix saving preferences with unrelated changes when gitaly timeouts became invalid.
-merge_request: 26292
-author:
-type: fixed

changelogs/unreleased/bw-board-query-by-id.yml

----
-title: Allow group/project board to be queried by ID via GraphQL
-merge_request: 24825
-author:
-type: added

changelogs/unreleased/bw-graphql-board-type.yml

----
-title: 'GraphQL: Add Board type'
-merge_request: 22497
-author: Alexander Koval
-type: added

changelogs/unreleased/cat-fix-env-passthrough-sast-205694.yml

----
-title: Fix variable passthrough in the SAST CI/CD template when using DinD
-merge_request: 25697
-author:
-type: fixed

changelogs/unreleased/cat-fix-namespaceid-import-39078.yml

----
-title: Fixes project import failures when user is not part of any groups
-merge_request: 26038
-author:
-type: fixed

changelogs/unreleased/changed-pages-ci-var.yml

----
-title: Added CI_MERGE_REQUEST_CHANGED_PAGE_* to Predefined Variables reference
-merge_request: 25256
-author:
-type: added

changelogs/unreleased/closed-issue-weight-grey.yml

----
-title: Board issue due dates appear grey for closed past-due issues
-merge_request: 25507
-author: rachelfox
-type: fixed

changelogs/unreleased/cluster-apps-0-9-0.yml

----
-title: Update cluster-applications to v0.9.0
-merge_request: 26242
-author:
-type: added

changelogs/unreleased/cluster-info-tabs.yml

----
-title: Split cluster info page into tabs
-merge_request: 25940
-author:
-type: changed

changelogs/unreleased/confapi-repo-push-mirror.yml

----
-title: Add support for configuring remote mirrors via API
-merge_request: 25825
-author: Rajendra Kadam
-type: added