Update CHANGELOG.md for 9.0.0

[ci skip]

changelogs/unreleased/26087-asciidoc-cicd-badges-snippet.yml

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-title: Added AsciiDoc Snippet to CI/CD Badges
-merge_request: 9164
-author: Jan Christophersen

changelogs/unreleased/26136-list-repository-tree-api-doc.yml

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-title: Make documentation of list repository tree API call more detailed
-merge_request: 9532
-author: Marius Kleiner

changelogs/unreleased/26206-fix-download-dropdown.yml

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-title: Set dropdown height fixed to 250px and make it scrollable
-merge_request: 9063
-author:

changelogs/unreleased/26286-most-recent-activity-profile-header.yml

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-title: Added 'Most Recent Activity' header to the User Profile page
-merge_request: 9189
-author: Jan Christophersen

changelogs/unreleased/26287-link-branch-in-calendar-activity.yml

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-title: Add Links to Branches in Calendar Activity
-merge_request: 9224
-author: Jan Christophersen

changelogs/unreleased/2629-show-public-rss-feeds-to-anonymous-users.yml

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-title: Show public RSS feeds to anonymous users
-merge_request: 9596
-author: Michael Kozono

changelogs/unreleased/26315-unify-labels-filter-behavior.yml

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-title: Unify issues search behavior by always filtering when ALL labels matches
-merge_request: 8849
-author:

changelogs/unreleased/26348-cleanup-navigation-order-groups.yml

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-title: Clean-up Groups navigation order
-merge_request: 9309
-author:

changelogs/unreleased/26348-cleanup-navigation-order.yml

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-title: Clean-up Project navigation order
-merge_request: 9272
-author:

changelogs/unreleased/26371-native-emojis-v3-code.yml

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-title: Use native unicode emojis
-merge_request:
-author:

changelogs/unreleased/26379-iid-param.yml

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-title: add :iids param to IssuableFinder (resolve technical dept)
-merge_request: 9222
-author: mhasbini

changelogs/unreleased/26500-informative-slack-notifications.yml

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-title: Add user & build links in Slack Notifications
-merge_request: 8641
-author: Poornima M

changelogs/unreleased/26651-cannot-move-project-into-group.yml

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-title: Specify in the documentation that only projects owners can transfer projects
-merge_request:
-author:

changelogs/unreleased/26703-todos-count.yml

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-title: show 99+ for large count in todos notification bell
-merge_request: 9171
-author: mhasbini

changelogs/unreleased/26705-filter-todos-by-manual-add.yml

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-title: Filter todos by manual add
-merge_request: 8691
-author: Jacopo Beschi @jacopo-beschi

changelogs/unreleased/26732-combine-deploy-keys-and-push-rules-and-mirror-repository-and-protect-branches-settings-pages.yml

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-title: Combined deploy keys, push rules, protect branches and mirror repository settings options into a single one called
-  Repository
-merge_request:
-author:

changelogs/unreleased/26744-add-omniauth-oauth2-generic-strategy.yml

-title: Add the oauth2_generic OmniAuth strategy
-merge_request: 9048
-author: Joe Marty
\ No newline at end of file

changelogs/unreleased/26790-label-color-todos.yml

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-title: fix background color for labels mention in todo
-merge_request: 9155
-author: mhasbini

changelogs/unreleased/26847-api-pipelines-use-basic.yml

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-title: Expose pipelines as PipelineBasic `api/v3/projects/:id/pipelines`
-merge_request: 8875
-author:

changelogs/unreleased/26875-builds-api-endpoint-skipped-scope.yml

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-title: Add all available statuses to scope filter for project builds endpoint
-merge_request:
-author: George Andrinopoulos