Update CHANGELOG.md for 12.3.0

[ci skip]

changelogs/unreleased/64799-disable-transfer-group.yml

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-title: Disable "Transfer group" button when no group is selected
-merge_request: 31387
-author: Jan Beckmann
-type: fixed

changelogs/unreleased/65063-Embeded-metrics-inconsistent-styles.yml

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-title: Fixed embeded metrics tooltip inconsistent styling
-merge_request: 31517
-author:
-type: fixed

changelogs/unreleased/65152-unfolded-lines-perf-improvement.yml

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-title: Support selective highlighting of lines
-merge_request: 32514
-author:
-type: performance

changelogs/unreleased/65192-enable-modsecurity-in-ingress.yml

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-title: Enable modsecurity in nginx-ingress apps
-merge_request: 15774
-author:
-type: added

changelogs/unreleased/65251-default-clusters-namespace_per_environment-column-to-true.yml

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-title: Default clusters namespace_per_environment column to true
-merge_request: 32139
-author:
-type: other

changelogs/unreleased/65304-add-pages-first-deployment-message.yml

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-title: Add warning about initial deployment delay for GitLab Pages sites
-merge_request: 32122
-author:
-type: added

changelogs/unreleased/65389-wrong-format-on-ms-teams-integration-push-events-with-multi-line-commit-messages.yml

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-title: Wrong format on MS teams integration push events with multi line commit messages
-merge_request: 32180
-author: Massimeddu Cireddu
-type: fixed

changelogs/unreleased/65412-add-support-for-line-charts.yml

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-title: Create component to display area and line charts in monitor dashboards
-merge_request: 31639
-author:
-type: added

changelogs/unreleased/65427-improve-system-notes-for-zoom-links.yml

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-title: Improve system notes for Zoom links
-merge_request: 31410
-author: Jacopo Beschi @jacopo-beschi
-type: changed

changelogs/unreleased/65764-add-missing-error-handling-to-add-list-dropdown-in-issue-boards.yml

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-title: Adds missing error handling
-merge_request: 16896
-author: toptalo
-type: fixed

changelogs/unreleased/65940-run-pipeline.yml

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-title: Run Pipeline button & API for MR Pipelines
-merge_request: 31722
-author:
-type: added

changelogs/unreleased/65988-optimize-snippet-listings.yml

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-title: Optimize queries for snippet listings
-merge_request: 32576
-author:
-type: performance

changelogs/unreleased/66022-git-clone-url-box-on-wiki-git-access-page-is-broken.yml

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-title: Fix broken git clone box on wiki git access page
-merge_request: 31898
-author:
-type: fixed

changelogs/unreleased/66037-deployment-user.yml

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-title: Return correct user for manual deployments
-merge_request: 32004
-author:
-type: fixed

changelogs/unreleased/66061-update-tooltip-of-detached-label-state.yml

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-title: Updates tooltip of 'detached' label/state
-merge_request:
-author:
-type: other

changelogs/unreleased/66067-pages-domain-doesnt-set-target-blank.yml

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-title: Makes custom Pages domain open as external link in new tab
-merge_request: 32130
-author: jakeburden
-type: fixed

changelogs/unreleased/66073-use-time-series-chart-instead-of-area-chart-in-panel_types.yml

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-title: Enable line charts in dashbaord panels and embedded charts
-merge_request: 31920
-author:
-type: added

changelogs/unreleased/66150-remove-dynamically-constructed-feature-flags-starting-with-promethe.yml

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-title: Remove dynamically constructed feature flags starting with prometheus_transaction_
-merge_request: 32395
-author: Jacopo Beschi @jacopo-beschi
-type: changed

changelogs/unreleased/66161-replace-expand-icons.yml

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-title: Replaced expand diff icons
-merge_request: 31907
-author:
-type: changed

changelogs/unreleased/66264-moved-issue-reference.yml

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-title: Use moved instead of closed in issue references
-merge_request: 32277
-author: juliette-derancourt
-type: changed