Update CHANGELOG.md for 12.0.0

[ci skip]

changelogs/unreleased/55447-validate-k8s-credentials.yml

----
-title: Validate Kubernetes credentials at cluster creation
-merge_request: 27403
-author:
-type: added

changelogs/unreleased/5615-non-admins-only-archieve-ce.yml

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-title: Add deletion protection setting column to application_settings table
-merge_request: 29268
-author:
-type: other

changelogs/unreleased/56737-commits-and-mr-events-on-jira-api.yml

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-title: Expose all current events properly on services API
-merge_request: 29736
-author: Zsolt Kovari
-type: fixed

changelogs/unreleased/56959-drop-project_auto_devops_domain.yml

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-title: Removes project_auto_devops#domain column
-merge_request: 28574
-author:
-type: other

changelogs/unreleased/56959-remove-auto-devops-domain-ci-variable.yml

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-title: Removes support for AUTO_DEVOPS_DOMAIN
-merge_request: 28460
-author:
-type: removed

changelogs/unreleased/57037-fix-mr-checkboxes-mobile-alignment.yml

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-title: Fix Merge Request merge checkbox alignment on mobile view
-merge_request: 28845
-author:
-type: fixed

changelogs/unreleased/57189-css-label-in-forms-with-bootstrap4.yml

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-title: Fix col-sm-* in forms to keep layout
-merge_request: 24885
-author: Takuya Noguchi
-type: fixed

changelogs/unreleased/57813-merge-request-tabs-do-not-handle-ctrl-click-correctly.yml

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-title: Allow command/control click to open link in new tab on Merge Request tabs
-merge_request: 29506
-author:
-type: fixed

changelogs/unreleased/57825-moving-an-issue-results-in-broken-image-links-in-comments.yml

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-title: Resolve moving an issue results in broken image links in comments
-merge_request: 28654
-author:
-type: fixed

changelogs/unreleased/58269-separate-update-patch.yml

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-title: Do not display Update app button when saving Knative domain name
-merge_request: 28904
-author:
-type: changed

changelogs/unreleased/58297-remove-extraneous-gitaly-calls-from-md-rendering.yml

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-title: Reduce Gitaly calls to improve performance when rendering suggestions
-merge_request: 29027
-author:
-type: performance

changelogs/unreleased/58404-set-default-max-depth-for-GraphQL.yml

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-title: 58404 - setup max depth for GraphQL
-merge_request: 25737
-author: Ken Ding
-type: added

changelogs/unreleased/58433-email-notifications-do-not-work-properly-issue-due-date.yml

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-title: Fix email notifications for user excluded actions
-merge_request: 28835
-author:
-type: fixed

changelogs/unreleased/58538-discussion-top-radius.yml

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-title: Fix border radius of discussions
-merge_request: 28490
-author:
-type: fixed

changelogs/unreleased/58632-fix-mr-widget-padding.yml

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-title: Fix padding in MR widget
-merge_request: 28472
-author:
-type: fixed

changelogs/unreleased/58941-use-gitlab-serverless-with-existing-knative-installation.yml

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-title: Enable function features for external Knative installations
-merge_request: 27173
-author:
-type: changed

changelogs/unreleased/58984-doc-missing-milestones-and-labels-links.yml

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-title: Document when milestones and labels links are missing
-merge_request: 29355
-author:
-type: other

changelogs/unreleased/59023-fix-web-ide-creating-branches-off-new-commits.yml

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-title: Fix IDE commit using latest ref in branch and overriding contents
-merge_request: 29769
-author:
-type: fixed

changelogs/unreleased/59026-replace-favicon.yml

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-title: Update favicon from next
-merge_request: 28601
-author: Jarek Ostrowski @jareko
-type: fixed

changelogs/unreleased/59105-padding-unclickable-pipeline-job.yml

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-title: Fix padding of unclickable pipeline dropdown items to match links
-merge_request:
-author:
-type: fixed