Set `projects.has_external_wiki` to `DEFAULT false` and `NOT NULL`

See merge request gitlab-org/gitlab!50916

This change contains migrations for `projects.has_external_wiki` to
become a `NOT NULL` column that defaults to `FALSE`.

This is possible after the PG Trigger added in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/49916 that always
maintains `projects.has_external_wiki` as a boolean and never a `NULL`.

It includes a data migration to set all historical `NULL` columns to be
either `TRUE` or `FALSE`.

The data migration also fixes the historical bad data for
`has_external_wiki`:
https://gitlab.com/gitlab-org/gitlab/-/issues/273574.

https://gitlab.com/gitlab-org/gitlab/-/issues/290715.

BulkImports: avoid infinity recursion on group migration

See merge request gitlab-org/gitlab!52931

Expand Linux cheat sheet's Networking section

See merge request gitlab-org/gitlab!52973

Refactor trigger block and spec

See merge request gitlab-org/gitlab!53151

Use codequality degradation factory

See merge request gitlab-org/gitlab!53069

Add btn-default class for the download button in graphs page

See merge request gitlab-org/gitlab!52857

The current subgroup migration strategy works iteratively, which means
that each level of a group tree is imported before moving to the next
level.

This becomes a problem when the target group is within the source group,
which creates a _infinity_ loop of import.

>> Example:

Given a group tree like:

- Group A
  - Group B
  - Group C
    - Group X
    - Group Y

If one decide to import the Group A into Group B, a recursion will
happen, making the import stop only when the depth limit is achieved or
some other database constraint, like the size of a group path.

- Group A
  - Group B
    - Group A
      - Group B
        - Group A
          - Group B
            - Group A
              - Group B
                - ...
              - Group C
                - Group X
                - Group Y
          - Group C
            - Group X
            - Group Y
      - Group C
        - Group X
        - Group Y
  - Group C
    - Group X
    - Group Y

To fix that, destination namespaces cannot be a descendant of the source
group.

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/300445

MRs that modify GraphQL complexity require a changelog

See merge request gitlab-org/gitlab!53124

Separate sections in user settings pages layout

See merge request gitlab-org/gitlab!53091

Fix typo in JSDoc comment

See merge request gitlab-org/gitlab!53164

Update deployment frequency graphs to use UTC dates

See merge request gitlab-org/gitlab!52919

This commit updates the deployment frequency charts to always use UTC
dates when computing offsets and when communicating with the API.

New Crowdin translations - 01 Feb 2021

See merge request gitlab-org/gitlab!53047

Remove ref_path from coverage CSV path

See merge request gitlab-org/gitlab!53063

Updated intro text

See merge request gitlab-org/gitlab!53098

Update Blue-Green Deploy Docs with Traffic Weight Shaping

See merge request gitlab-org/gitlab!52795

Serialize reference attribute on epics autocomplete endpoint

See merge request gitlab-org/gitlab!49744

Add btn-icon class for action buttons in the user profile

See merge request gitlab-org/gitlab!52901

Add integration types table and polish some content

See merge request gitlab-org/gitlab!51867

Also polished some content.

Add some additional information about viewing Group level Packages

See merge request gitlab-org/gitlab!53071

This commit update "Perform" to be "Performs" in JSDoc comments.

Update test case issue links for epic milestone e2e spec

See merge request gitlab-org/gitlab!53150

UI text  - settings - deploy keys

See merge request gitlab-org/gitlab!52830

- Improve UI text - deploy keys - shared

- Add changelog UI text

- TW review - wording and syntax

- Update translations gitlab.pot

- Update spec files - deploy keys

- Update component - deploy keys

- Update docs - deploy keys

- Update empty_state view

- Make text translatable

Add award emoji to epics in GraphQL

See merge request gitlab-org/gitlab!52922

Simplify BulkImports::Pipeline::Context

See merge request gitlab-org/gitlab!52833

Update mini pipeline selectors to use data-testid

See merge request gitlab-org/gitlab!53017

Add UTC support to date add/subtract utilities

See merge request gitlab-org/gitlab!53053

This commit update all date addition/subtraction utilities to optionally
support perfoming the calculation with UTC dates, which ignores
Daylight Saving Time.

Remove space next to the icon in email button on admin/users page

See merge request gitlab-org/gitlab!52451

Update the specs and also apply
some styling to the table to match
previous implementation.

Create worker to handle group repository storage moves

See merge request gitlab-org/gitlab!52701

Don't require sidekiq-middleware in fixture file that doesn't use it

See merge request gitlab-org/gitlab!52908

Global Search - UX Refresh for Sort Button

See merge request gitlab-org/gitlab!52387