imageLoading was being set incorrectly (every time the item appeared).
This meant that even if the image was not loading, the loading
spinner would appear if the image appeared in view again.

This commit changes the logic so that we only set imageLoading if the
image has never appeared in view.

This commit also adds and reorganises some tests to ensure this path is
covered.

Merge branch '197314-the-board-list-issuable-sidebar-and-board-list-settings-overlap-when-both-are-opened' into 'master'

Add event to handle closing all board sidebars

Closes #197314

See merge request gitlab-org/gitlab!26886

This was made to avoid having to _manually_ close all sidebars (to open
a new one for example), and to prevent having two or more sidebars open
at the same time.

Each of the sidebars components are listening to a 'sidebars.closeAll'
event that has an optional `omit` property to avoid closing a sidebar
if not needed, for example, when browsing through issues.

Resolve "Flaky test `elastic_indexer_worker_spec.rb`"

Closes #213740

See merge request gitlab-org/gitlab!29211

Populate canonical emails

Closes #205383

See merge request gitlab-org/gitlab!28298

Correct format for curl in epic documentation

See merge request gitlab-org/gitlab!29057

Fix keyboard shortcut to navigate to dashboard activity

Closes #207185

See merge request gitlab-org/gitlab!28985

Resolve "Audit Log date picker has no background color"

Closes #213827

See merge request gitlab-org/gitlab!29153

But index_record_service_spec still flaky

Class level caching, classes being created in tests and then stored in a
global registry of classes leads to bad results. The deleted test is
messing with a class level cache and creating classes, the previous
search method we switched out was using was looking through a global
registry of classes.

Add cluster management project template

See merge request gitlab-org/gitlab!25318

Project mirrors: Remove unused container

See merge request gitlab-org/gitlab!29035

Load GitLabSchema as workaround for errors

See merge request gitlab-org/gitlab!29208

Add policy read_cross_project specs for anonymous

See merge request gitlab-org/gitlab!29198

Make "Value Stream" the top item in group-level analytics sidebar menu

Closes #210317

See merge request gitlab-org/gitlab!27277

.com has a subscription expired banner

See merge request gitlab-org/gitlab!28238

Add Terms intermediary page

Closes #212145

See merge request gitlab-org/gitlab!28248

Update GitLab Shell to v12.1.0

See merge request gitlab-org/gitlab!29167

Remove ProjectAuthorization.roles_stats method

Closes #213083

See merge request gitlab-org/gitlab!29120

Add annotations config generator

See merge request gitlab-org/gitlab!29085

Ensure members mapper always runs on Project Import

See merge request gitlab-org/gitlab!29046

Background migration to generate a canonical email based
on the user's primary email. "Canonical" means the Agent
part of the email address omitting `.` and anything after
any `+`. Only applies to Gmail since they are a service
that allows `.` and ignores anything after `+` in the Agent
and all variations arrive in the same inbox.

Improvements to make review_merge_request_spec more reliable

See merge request gitlab-org/gitlab!28974

Add Health Status badge in Epic tree

See merge request gitlab-org/gitlab!27869

Fix IDE on empty repo

Closes #27915

See merge request gitlab-org/gitlab!25463

Load code navigation for merge request diffs

Closes #119036

See merge request gitlab-org/gitlab!28083

Quarantine broken test

See merge request gitlab-org/gitlab!29217

Add artefacts wildcard case in documentation

Closes gitlab-runner#5025

See merge request gitlab-org/gitlab!25719

Rename lfs_administration doc

Closes #213143

See merge request gitlab-org/gitlab!28896

Rename doc to index.md and adjust all links
to the doc.

See https://gitlab.com/gitlab-org/gitlab/-/issues/213676
And https://gitlab.com/gitlab-org/gitlab/-/issues/213277

Seed metrics dashboard with mulit metric example

See merge request gitlab-org/gitlab!28490

Clarify when variables will be overrode

See merge request gitlab-org/gitlab!29005

Move test coverage for Enforced SSO Access to feature level

Closes #205455

See merge request gitlab-org/gitlab!29127

Also remove the tests from end-to-end level

Fix typo Acylic->Acyclic

See merge request gitlab-org/gitlab!29178

The errors we see are due to a lack of thread safety.

We can remove this workaround when we convert the schema to use
the new query interpreter runtime.

https://gitlab.com/gitlab-org/gitlab/-/issues/211478#note_320636547

See:
- https://gitlab.com/gitlab-org/gitlab/-/issues/211478
- https://gitlab.com/gitlab-org/gitlab/-/issues/210556

Merge branch '207167-docs-fy2021-q1-okr-audit-and-improve-high-traffic-access-documentation' into 'master'

Update our GitLab and SSH documentation

See merge request gitlab-org/gitlab!27933