Update CHANGELOG.md for 12.8.0

[ci skip]

changelogs/unreleased/ali-add-type-to-pages-domains.yml

----
-title: Update PagesDomains data model for serverless domains
-merge_request: 23943
-author:
-type: changed

changelogs/unreleased/ali-fix-cloud-run-doc-links.yml

----
-title: Update broken links to Cloud Run for Anthos documentation
-merge_request: 25159
-author:
-type: fixed

changelogs/unreleased/ali-serverless-domains-be-1.yml

----
-title: Add admin settings panel for instance-level serverless domain (behind feature flag)
-merge_request: 21222
-author:
-type: added

changelogs/unreleased/allow-minimum-processes-in-sidekiq-cluster.yml

----
-title: Allow setting minimum concurrency for sidekiq-cluster processes
-merge_request: 23408
-author:
-type: added

changelogs/unreleased/allowed-to-fail-warning-color.yml

----
-title: Changed color of allowed to fail badge from danger to warning
-merge_request: !23437
-author:
-type: changed

changelogs/unreleased/an-sidekiq-query.yml

----
-title: Add experimental --queue-selector option to sidekiq-cluster
-merge_request: 18877
-author:
-type: changed

changelogs/unreleased/archive-404.yml

----
-title: Return 404 when repository archive cannot be retrieved
-merge_request: 23926
-author:
-type: fixed

changelogs/unreleased/avoid-double-credential-encoding-on-project-importing.yml

----
-title: Avoid double encoding of credential while importing a Project by URL
-merge_request: 24514
-author:
-type: fixed

changelogs/unreleased/avoid-using-gl-object.yml

----
-title: Fix outdated MR security warning message
-merge_request: 23496
-author:
-type: fixed

changelogs/unreleased/broadcast-api-auth.yml

----
-title: Allow users to read broadcast messages via API
-merge_request: 23298
-author: Rajendra Kadam
-type: changed

changelogs/unreleased/bump-ado-image-for-helm-values-fix.yml

----
-title: Fix overriding the image pull policy from a values file for Auto Deploy
-merge_request: 25271
-author: robcalcroft
-type: fixed

changelogs/unreleased/bump-deploy-0-9-1.yml

----
-title: Bump auto-deploy-image for Auto DevOps deploy to 0.9.1
-merge_request: 24231
-author:
-type: other

changelogs/unreleased/bvl-correct-thread-count.yml

----
-title: Fix sidekiq jobs not always getting a database connection when running with low concurrency
-merge_request: 25261
-author:
-type: fixed

changelogs/unreleased/bvl-remove-project-object-from-error-logging.yml

----
-title: Don't leak entire objects into the error log when rendering markup fails
-merge_request: 24599
-author:
-type: fixed

changelogs/unreleased/bvl-remove-request-deadline-ff.yml

----
-title: Don't allow Gitaly calls to exceed the worker timeout set for unicorn or puma
-merge_request: 23510
-author:
-type: performance

changelogs/unreleased/bw-fix-board-sorting.yml

----
-title: Ensure board lists are sorted consistently
-merge_request: 24637
-author:
-type: fixed

changelogs/unreleased/bw-fix-rake-descriptions.yml

----
-title: Make rake -T output more consistent
-merge_request: 23550
-author:
-type: other

changelogs/unreleased/bw-merge-request-permission.yml

----
-title: Task lists work correctly again on closed MRs
-merge_request: 23714
-author:
-type: fixed

changelogs/unreleased/cilium-managed-apps.yml

----
-title: Add cilium to the managed cluster apps template
-merge_request: 22557
-author:
-type: added

changelogs/unreleased/custom-dashboard-validation.yml

----
-title: Add validation for custom PrometheusDashboard
-merge_request: 22893
-author:
-type: added