Update CHANGELOG.md for 12.8.0

[ci skip]

changelogs/unreleased/3142-add-cluster-loading-icon.yml

----
-title: Add loading icon to clusters being created
-merge_request: 24370
-author:
-type: added

changelogs/unreleased/31526-skip-if-needed-job-skipped.yml

----
-title: Prevent DAG builds to run after skipped need build
-merge_request: 23405
-author:
-type: fixed

changelogs/unreleased/31832-improve-performance-of-the-container-registry-delete-tags-api.yml

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-title: Improve performance of the Container Registry delete tags API
-merge_request: 23325
-author:
-type: performance

changelogs/unreleased/31914-graphql-todo-bulk-restore-pd.yml

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-title: Add GraphQL mutation to restore multiple todos
-merge_request: 23950
-author:
-type: added

changelogs/unreleased/32079-misleading-suggestion-is-created-when-made-at-the-last-line-of-a-fi.yml

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-title: Fixes a new line issue with suggestions in the last line of a file
-merge_request: 22732
-author:
-type: fixed

changelogs/unreleased/32714-snippets-ux-improvement-empty-state.yml

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-title: Update snippets empty state and remove explore snippets button
-merge_request: 24764
-author:
-type: other

changelogs/unreleased/32714-snippets-ux-improvement.yml

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-title: Improve UX of optional fields in Snippets form
-merge_request: 24762
-author:
-type: other

changelogs/unreleased/33071-update-kaminari-templates.yml

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-title: Update Kaminari templates to match gl-pagination's markup
-merge_request: 23582
-author:
-type: other

changelogs/unreleased/33128-cannot-find-projects-within-subgroups-when-you-select-a-top-level-g.yml

----
-title: Query projects of subgroups in productivity analytics
-merge_request: 24335
-author:
-type: fixed

changelogs/unreleased/33257-prevent-accidental-deletions-via-soft-delete-for-groups-api.yml

----
-title: Add API endpoints for 'soft-delete for groups' feature
-merge_request: 19430
-author:
-type: added

changelogs/unreleased/33257-prevent-accidental-deletions-via-soft-delete-for-groups-ui-changes.yml

----
-title: Add UI for 'soft-delete for groups' feature
-merge_request: 19483
-author:
-type: added

changelogs/unreleased/33596-add-pipeline-metadata-to-the-package-registry-ui.yml

----
-title: Packages published to the package registry via CI/CD with a CI_JOB_TOKEN will
-  display pipeline information on the details page
-merge_request: 22485
-author:
-type: added

changelogs/unreleased/34021-environments-dropdown-remove-feature-flag.yml

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-title: Enable search and filter in environments dropdown in monitoring dashboard
-merge_request: 23942
-author:
-type: added

changelogs/unreleased/34262-readonly-ldap-attributes.yml

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-title: Make name, email, and location attributes readonly for LDAP enabled instances
-merge_request: 24049
-author:
-type: changed

changelogs/unreleased/34353-graphql-mutation-update-image-diff-note.yml

----
-title: Add updateImageDiffNote mutation
-merge_request: 24027
-author:
-type: added

changelogs/unreleased/34722-dashboard-projectscontroller-should-tolerate-single-gitaly-node-fai.yml

----
-title: Fix pipeline status loading errors on project dashboard page caused by Gitaly
-  connection failures
-merge_request: 23378
-author:
-type: fixed

changelogs/unreleased/34722-project-icon-lookup-fix.yml

----
-title: Fix 503 errors caused by Gitaly failures during project_icon lookup
-merge_request: 23930
-author:
-type: fixed

changelogs/unreleased/34723-visually-differentiate-blocked-issues.yml

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-title: Add blocked icon on issue board card
-merge_request: 24420
-author:
-type: added

changelogs/unreleased/34802-switch-cloud-providers.yml

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-title: Allow to switch between cloud providers in cluster creation screen
-merge_request: 23362
-author:
-type: changed

changelogs/unreleased/35288-update-metrics-dashboard-dropdowns.yml

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-title: Added search box to dashboards dropdown in monitoring dashboard
-merge_request: 23906
-author:
-type: added