Merge branch '259607-update-assignee-to-use-gl-class' into 'master'

Change assignee in mr list to use gl-class

See merge request gitlab-org/gitlab!44502

app/views/projects/merge_requests/_merge_request.html.haml

@@ -53,7 +53,7 @@
             = link_to merge_request_path(merge_request), class: "has-tooltip", title: _('Cannot be merged automatically') do
               = sprite_icon('warning-solid')
         - if merge_request.assignees.any?
-          %li.d-flex
+          %li.gl-display-flex
             = render 'shared/issuable/assignees', project: merge_request.project, issuable: merge_request
         - if Feature.enabled?(:merge_request_reviewers, @project) && merge_request.reviewers.any?
           %li.gl-display-flex.issuable-reviewers