Update CHANGELOG.md for 9.1.0

[ci skip]

changelogs/unreleased/28991-viewing-old-wiki-page-version-edit-button-exists.yml

----
-title: When viewing old wiki page version, edit button should be disabled
-merge_request: 9966 
-author: TM Lee

changelogs/unreleased/29014-create-issue-form-buttons-misaligned-on-mobile.yml

----
-title: Fix create issue form buttons are misaligned on mobile
-merge_request: 9706
-author: TM Lee

changelogs/unreleased/29043-upgrade-vue-and-remove-warnings.yml

----
-title: Upgrade VueJS to v2.2.4 and disable dev mode warnings
-merge_request: 9981
-author:

changelogs/unreleased/29046-fix-github-importer-open-prs.yml

----
-title: Fix GitHub Import deleting branches for open PRs from a fork
-merge_request: 9758
-author:

changelogs/unreleased/29116-maxint-error.yml

----
-title: Fix projects_limit RangeError on user create
-merge_request:
-author: Alexander Randa

changelogs/unreleased/29128-profile-page-icons.yml

----
-title: Add helpful icons to profile events
-merge_request:
-author:

changelogs/unreleased/29137-bulk-perform-async-should-specify-queue.yml

----
-title: Make authorized projects worker use a specific queue instead of the default one
-merge_request: 9813
-author:

changelogs/unreleased/29162-refactor-dropdown-milestone-spec.yml

----
-title: Refactor dropdown_milestone_spec.rb
-merge_request:
-author: George Andrinopoulos

changelogs/unreleased/29189-discussion-button.yml

----
-title: Fix alignment of resolve button
-merge_request:
-author:

changelogs/unreleased/29209-sign-up-form-name.yml

----
-title: Change label for name on sign up form
-merge_request:
-author:

changelogs/unreleased/29328-fix-transient-failure-in-model-user-spec.yml

----
-title: Add custom attributes in factories
-merge_request: 9892
-author: George Andrinopoulos

changelogs/unreleased/29341-add-metrics-button-env-overview.yml

----
-title: Add metrics button to environments overview page
-merge_request: 10234
-author:

changelogs/unreleased/29364-private-projects-mr-fix.yml

----
-title: Don’t show source project name when user does not have access
-merge_request:
-author:

changelogs/unreleased/29405-fix-project-wiki-update.yml

----
-title: Fix Project Wiki update
-merge_request: 9990
-author: Dongqing Hu

changelogs/unreleased/29414-fix-toggle-discussion-link-jump.yml

----
-title: Update toggle buttons to be <button>
-merge_request:
-author:

changelogs/unreleased/29428-new-directory-from-existing-branch.yml

----
-title: New directory from interface on existing branch
-merge_request: 9921
-author: Jacopo Beschi @jacopo-beschi

changelogs/unreleased/29432-prevent-click-disabled-btn.yml

----
-title: Fix project title validation, prevent clicking on disabled button
-merge_request: 9931
-author:

changelogs/unreleased/29438-fix-trigger-webhook-for-ref-with-dot.yml

----
-title: Fix trigger webhook for ref with a dot
-merge_request: 10001
-author: George Andrinopoulos

changelogs/unreleased/29469-message-for-project-x-will-be-deleted-should-include-namespace.yml

----
-title: Display full project name with namespace upon deletion
-merge_request:
-author:

changelogs/unreleased/29483-spam-check-only-title-and-description.yml

----
-title: Spam check only when spammable attributes have changed
-merge_request:
-author: