Fix for creating a project through API when import_url is nil

Closes #29121

See merge request !9841

Update feature visibility spec for projects edit page

See merge request !9787

Document gitaly.socket_path setting

See merge request !9858

Prevent more than one issue tracker to be active for the same project

Closes #22797

See merge request !9669

Resolve "Can't select a mirror user"

See merge request !9854

Change label for name on sign up form

Closes #29209

See merge request !9845

Add zip/unzip as dependencies for Pages source installations

Closes #28440

See merge request !9828

Add a section on issue/MR labeling in CONTRIBUTING.md

Closes #25097

See merge request !9850

In EE, `@users` can be an array at the point where we remove the current
user, because it can do a permissions check on the users for project
mirroring.

Fix this in CE by only using array methods, not AR methods. We can't use
`delete` because that uses `Object#equal?`, which isn't true in this
case.

Adds information about architecture step.

See merge request !9844

Prevent dropdown from closing when user clicks in a build.

Closes #24166

See merge request !9834

The API was returning 500 when `nil` is passed for the `import_url`.

In fact, it was `Gitlab::UrlSanitizer.valid?` which was throwing a
`NoMethodError` when `nil` value was passed.

Fix "passed with warnings" stage status on MySQL

Closes #28603

See merge request !9802

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/25097

[ci skip]

Add confirmation dialogs guidelines in UX copy

See merge request !9833

Flush out the update guide from 8.17 - 9.0

See merge request !9823

Missed removing one of the redundant lines

Fix redundant wording.
Clean up code blocks and links.

Get view type based on diff_view Cookie

Closes #27899

See merge request !9821

Only check new migrations in 'rake downtime_check'

See merge request !9785

Convert data attributes in search_bar.html.haml

Closes #29082

See merge request !9819

Order milestone issues by position ascending in api

Closes #28847

See merge request !9635

Remove inline-block styling from dropdown avatars

Closes #29048

See merge request !9840

Removes `:visible` from selector
Adds CHANGELOG entry
Removes iife

[#29014] Create issue form buttons are misaligned on mobile

Closes #29014

See merge request !9706

Diff avatar improvements

Closes #29237, #29238, and #29243

See merge request !9829

Update emojis to use harmony modules (import/export)

See merge request !9784

respect offset and limit query params for infinite lists

Closes #28030

See merge request !9540

Document "How to get your MR reviewed, approved, and merged"

See merge request !9839

[ci skip]
Signed-off-by: Rémy Coutable <remy@rymai.me>