Change all occurrences of ApplicationHelper#avatar_icon to use a User object where possible

Closes #42800

See merge request gitlab-org/gitlab-ce!16976

Remove ignore_column :data from Event

Closes #38135

See merge request gitlab-org/gitlab-ce!17094

Change SQL for expired artifacts to use new ci_job_artifacts.expire_at

See merge request gitlab-org/gitlab-ce!16578

Respect description and visibility when creating project from template

Closes #42601

See merge request gitlab-org/gitlab-ce!16820

Resolve "Remove notification settings for groups and projects you were previously a member of"

Closes #42481

See merge request gitlab-org/gitlab-ce!16906

QA with runner cloning the repo with a deploy key

Closes gitlab-qa#148

See merge request gitlab-org/gitlab-ce!16859

Allow including custom attributes in API responses

See merge request gitlab-org/gitlab-ce!16526

Add information about projects when searching in wiki_blobs, blobs, commits scopes

Closes #42934

See merge request gitlab-org/gitlab-ce!17095

Display a link to external issue tracker when enabled

Closes #37050

See merge request gitlab-org/gitlab-ce!17030

API: Get refs for a particular commit

Closes #18014

See merge request gitlab-org/gitlab-ce!15026

Add a security harness script

Closes #43220

See merge request gitlab-org/gitlab-ce!17097

Resolve "Diff file navigation shows renamed files as deleted"

Closes #42314

See merge request gitlab-org/gitlab-ce!17091

Update database_mysql.md to remove conflicting recommendation

See merge request gitlab-org/gitlab-ce!17101

Remove unused code in profile.js

See merge request gitlab-org/gitlab-ce!17009

This script toggles a Git pre-push hook that will prevent pushing to
remotes other than dev when the harness is enabled.

Remove problematic LDAP::Person validation for new strategy

Closes #42412 and #42359

See merge request gitlab-org/gitlab-ce!16727

Remove Sentry reporting for query limiting

See merge request gitlab-org/gitlab-ce!17092

Fix settings panels not expanding when fragment hash linked

Closes #43198

See merge request gitlab-org/gitlab-ce!17074

Closes #38135.

Fully enable nginx-ingress metrics

Closes #43189

See merge request gitlab-org/gitlab-ce!17069

This essentially allows to pass both user and email, so that we can
either prefer the user to retrieve the avatar or (if user is not
present) fall back to the email lookup.

Closes #42800.

Rather radical but avoids n+1 queries in the rather common case we want
to include information about the author.

We want to drop the generic #avatar_icon helper that supports both an email
and a user object being passed in. Instead, we want to explicitly use the #avatar_icon_for_user
and #avatar_icon_for_email helpers depending on what we have at hand.
This allows us to avoid unnecessary database queries (e.g. call
User.find_by_any_email if we already have the user).

In situations like here, this makes it less convenient to use.

We need to keep the email lookup as we want to fall back to displaying
the gravatar result for a given email if the user does not exist.