Update CHANGELOG.md for 8.17.0

[ci skip]

changelogs/unreleased/27822-default-bulk-assign-labels.yml

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-title: Add default labels to bulk assign dropdowns
-merge_request:
-author:

changelogs/unreleased/27873-when-a-commit-appears-in-several-projects-commit-comments-are-shared-across-projects.yml

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-title: Only return target project's comments for a commit
-merge_request:
-author:

changelogs/unreleased/27880-pipelines-table-not-showing-commit-branch.yml

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-title: Fixes Pipelines table is not showing branch name for commit
-merge_request:
-author:

changelogs/unreleased/27883-autocomplete-seems-to-not-trigger-when-at-character-is-part-of-an-autocompleted-text.yml

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-title: Trigger autocomplete after selecting a slash command
-merge_request: 9117
-author:

changelogs/unreleased/27922-cmd-click-todo-doesn-t-work.yml

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-title: Fix regression where cmd-click stopped working for todos and merge request
-  tabs
-merge_request:
-author:

changelogs/unreleased/27925-fix-mr-stray-pipelines-api-request.yml

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-title: Fix stray pipelines API request when showing MR
-merge_request:
-author:

changelogs/unreleased/27932-merge-request-pipelines-displays-json.yml

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-title: Fix Merge request pipelines displays JSON
-merge_request:
-author:

changelogs/unreleased/27939-fix-current-build-arrow.yml

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-title: Fix current build arrow indicator
-merge_request:
-author:

changelogs/unreleased/27943-contribution-list-on-profile-page-is-aligned-right.yml

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-title: Fix contribution activity alignment
-merge_request:
-author:

changelogs/unreleased/27947-missing-margin-between-loading-icon-and-text-in-merge-request-widget.yml

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-title: Add space between text and loading icon in Megre Request Widget
-merge_request: 9119
-author:

changelogs/unreleased/27955-mr-notification-use-pipeline-language.yml

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-title: Show Pipeline(not Job) in MR desktop notification
-merge_request:
-author:

changelogs/unreleased/27963-tooltips-jobs.yml

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-title: Fix tooltips in mini pipeline graph
-merge_request:
-author:

changelogs/unreleased/27966-branch-ref-switcher-input-filter-broken.yml

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-title: Display loading indicator when filtering ref switcher dropdown
-merge_request:
-author:

changelogs/unreleased/27987-skipped-pipeline-mr-graph.yml

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-title: Show pipeline graph in MR widget if there are any stages
-merge_request:
-author:

changelogs/unreleased/27991-success-with-warnings-caret.yml

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-title: Fix icon colors in merge request widget mini graph
-merge_request:
-author:

changelogs/unreleased/28029-improve-blockquote-formatting-on-emails.yml

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-title: Improve blockquote formatting in notification emails
-merge_request:
-author:

changelogs/unreleased/28032-tooltips-file-name.yml

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-title: Adds container to tooltip in order to make it work with overflow:hidden in
-  parent element
-merge_request:
-author:

changelogs/unreleased/28059-add-pagination-to-admin-abuse-reports.yml

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-title: Restore pagination to admin abuse reports
-merge_request:
-author:

changelogs/unreleased/395-fix-notification-when-group-set-to-watch.yml

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-title: Fix notifications when set at group level
-merge_request: 6813
-author: Alexandre Maia

changelogs/unreleased/8-15-stable.yml

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-title: Ensure export files are removed after a namespace is deleted
-merge_request: 
-author: