Improve tests and address other feedback

- Fix tests for #index
- Add and DRY up fixtures
- Eliminate some redundant runs of shared examples
  to speed things up.

- Add ISSUABLE_TYPE const
- Add projectSplit computed

Update tests
Add changelog

Add endpoint to get desired payload
Add namespace and project props

Use help_page_path for links in PipelineTourSuccessModal

See merge request gitlab-org/gitlab!47025

Quarantine create_project_spec.rb on staging only

See merge request gitlab-org/gitlab!47223

Remove duplicated BS display properties from Merge Request title

See merge request gitlab-org/gitlab!47124

Cleanup welcome helper method

See merge request gitlab-org/gitlab!47184

Remove duplicated BS display properties from Nav and Milestones

See merge request gitlab-org/gitlab!47129

Update coverage fuzzing docs and enable flag

See merge request gitlab-org/gitlab!46651

Bugfix recipients of design comment notifications

See merge request gitlab-org/gitlab!46642

Previously only users who were mentioned in a design comment would
receive an email notification. Now it will be all users who have
uploaded a version of the design, commented on the design, or been
mentioned in the design (in addition to the regular project and user
notification settings).

https://gitlab.com/gitlab-org/gitlab/-/issues/217095

Change confusing not updated milestone in API docs

See merge request gitlab-org/gitlab!47186

Add rails app code for revocation API access

See merge request gitlab-org/gitlab!46337

Add rails application configuration providing access to revocation API

GraphQL Snippets: use Global-ID scalar

See merge request gitlab-org/gitlab!36117

This uses the new GlobalID scalar types in the Snippets code. The
benefits of this are:

- More informative types. A reader of our schema, or our queries can see
  what a valid value will be.
- Safer resolution and mutation. When using this type we guarantee that
  our code will only encounter valid values, from our own namespace, and
  when using the parameterized IDs, that they cannot refer to other
  kinds of object.

Include SnowplowHelpers only when :snowplow metadata was provided

See merge request gitlab-org/gitlab!47177

Improve the container registry client

See merge request gitlab-org/gitlab!46989

Populate `has_vulnerabilities` values

See merge request gitlab-org/gitlab!46890

Configure more feature flags

See merge request gitlab-org/gitlab!47208

Reorganised and updated with list view data

See merge request gitlab-org/gitlab!47204

The link formatting was wrong in a couple of files.

Improve sign-up restrictions docs

See merge request gitlab-org/gitlab!47149

Documentation for Usage Ping aggregated metrics

See merge request gitlab-org/gitlab!46953

Change wording for git tag parameter in release API docs

See merge request gitlab-org/gitlab!47165

Quarantine a broken spec

See merge request gitlab-org/gitlab!47219

See https://gitlab.com/gitlab-org/gitlab/-/issues/280554.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Add docs for track_event with multiple values

See merge request gitlab-org/gitlab!47180

Mention Terraform List in docs

See merge request gitlab-org/gitlab!47197

Edited instructions for style compliance

See merge request gitlab-org/gitlab!47141

Update grape-path-helpers to v1.5.0

See merge request gitlab-org/gitlab!47121