EE: Trace as artifacts (FileStorage and ObjectStorage)

Closes #4171

See merge request gitlab-org/gitlab-ee!4258

See https://gitlab.com/gitlab-org/gitlab-ce/issues/39118

Conflicts:
	app/views/ci/variables/_form.html.haml
	app/views/ci/variables/_table.html.haml
	ee/app/views/ci/variables/_environment_scope.html.haml
	spec/javascripts/ci_variable_list/ci_variable_list_ee_spec.js
	spec/javascripts/fixtures/projects.rb

Part of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4110

Part of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4110

If using gravatar.com, both plain_url and ssl_url in settings are now
served via HTTPS. Make this the default.

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/42157
Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/41989

Finishes tabs & table
Updates e2e tests

Add tests
Update empty state
[ci skip]

The dropdown options `Issues assigned to me` and `Issues I've created` in project search are now
hidden when issues are disabled on the project.

Fix fixture

After merging a MR the close button is hidden, without reloading the page.

We need to cleanup after each execution so we can still re-use the same
paths and prevent collision with the on disk validation

Extracted `@request.env['devise.mapping'] = Devise.mappings[:user]` and `Rails.application.env_config['devise.mapping'] = Devise.mappings[:user]`
in our tests into the helper method `set_devise_mapping`

This reverts merge request !11963