Update CHANGELOG.md for 12.8.0

[ci skip]

changelogs/unreleased/202101-make-project-buttons-fit-in-1-row.yml

----
-title: Rename 'Kubernetes configured' button
-merge_request: 24487
-author:
-type: changed

changelogs/unreleased/202109.yml

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-title: update main javascript file to only apply right sidebar class when an aside
-  is present
-merge_request:
-author: Oregand
-type: fixed

changelogs/unreleased/202696-only-display-y-axis-of-data-value-ranges-for-charts.yml

----
-title: Display the y-axis on the range of data value in the chart
-merge_request: 24953
-author:
-type: added

changelogs/unreleased/2035-frontend-remove-feature-flag-code.yml

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-title: Add blocking issues feature
-merge_request: 24460
-author:
-type: added

changelogs/unreleased/204729-nomethoderror-undefined-method-oauth_applications-for-nil-nilclass.yml

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-title: Fix 500 error while accessing Oauth::ApplicationsController without a valid session
-merge_request: 24775
-author:
-type: fixed

changelogs/unreleased/204740-migrate-fa-spinner-to-spinner-within-app-views-projects-cycle_anal.yml

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-title: Update loading icon in Value Stream Analytics view
-merge_request: 24861
-author:
-type: other

changelogs/unreleased/204856-replicating-objects-in-object-storage-schedules-removal-and-re-syn.yml

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-title: 'Geo: Don''t clean up files in object storage when Geo is responsible of syncing
-  them'
-merge_request: 24901
-author:
-type: fixed

changelogs/unreleased/205248-remove-ci-status-from-project-dashboard.yml

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-title: Remove CI status from Projects Dashboard
-merge_request: 25225
-author: George Thomas @thegeorgeous
-type: removed

changelogs/unreleased/21371-auto-generated-wiki-commit-message-having-html-encoded-entities.yml

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-title: Auto generated wiki commit message containing HTML encoded entities
-merge_request: 21371
-author: 2knal
-type: other

changelogs/unreleased/21705-number-of-snippets-in-the-snippets-page-is-wrong.yml

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-title: Fix bug with snippet counts not being scoped to current authorisation
-merge_request: 21705
-author:
-type: fixed

changelogs/unreleased/21765-deploy-token-add-type.yml

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-title: Add deploy_token_type column to deploy_tokens table.
-merge_request: 23530
-author:
-type: added

changelogs/unreleased/21765-group-token-architecture.yml

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-title: Update deploy token architecture to introduce group-level deploy tokens.
-merge_request: 23460
-author:
-type: added

changelogs/unreleased/21801-migrate-epic-and-epic-notes-mentions-to-epic-user-mentions-table.yml

----
-title: Migrate epic, epic notes mentions to respective DB table
-merge_request: 22333
-author:
-type: changed

changelogs/unreleased/21901-support-for-toc-in-readme-files.yml

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-title: Support for table of contents tag in GitLab Flavored Markdown
-merge_request: 24196
-author:
-type: added

changelogs/unreleased/22113-improve-keyboard-shortcuts-or-allow-them-to-be-disabled.yml

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-title: Allow keyboard shortcuts to be disabled
-merge_request: 18782
-author:
-type: added

changelogs/unreleased/22406-update-existing-subgroups-to-match-visibility-level-of-parent-v2.yml

----
-title: Fix visibility levels of subgroups to be not higher than their parents' level
-merge_request: 22889
-author:
-type: other

changelogs/unreleased/23068-ability-to-delete-identities-for-user.yml

----
-title: Add delete identity endpoint on the users API
-merge_request: 24122
-author:
-type: added

changelogs/unreleased/23140-productivity-analytics-limit-graph-scales-to-whole-numbers.yml

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-title: Limit productivity analytics graph y-axis scale to whole numbers
-merge_request: 23140
-author:
-type: fixed

changelogs/unreleased/23296-add-ci-variables-server-port-protocol.yml

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-title: Add CI variables to provide GitLab port and protocol
-merge_request: 23296
-author: Aidin Abedi
-type: added

changelogs/unreleased/23315-routing-changes-and-pagination-for-container-registry.yml

----
-title: Add show routes for group and project repositories_controllers and add pagination
-  to the index responses
-merge_request: 23151
-author:
-type: added