Apply GitLab UI button styles to buttons in ee/app/views/shared/issuable directory

Instructions

For instructions about how to apply GitLab UI button styles to the button instances on these templates, see the epic &4001 (closed).

Files in directory with buttons that needs migration

• ee/app/views/shared/issuable/_approved_by_dropdown.html.haml (does not exist)
• ee/app/views/shared/issuable/_approver_dropdown.html.haml
• ee/app/views/shared/issuable/_board_create_list_dropdown.html.haml
• ee/app/views/shared/issuable/_bulk_update_button.html.haml
• ee/app/views/shared/issuable/_filter_epic.html.haml
• ee/app/views/shared/issuable/_filter_iteration.html.haml
• ee/app/views/shared/issuable/_filter_weight.html.haml
• ee/app/views/shared/issuable/_group_bulk_update_sidebar.html.haml
• ee/app/views/shared/issuable/_remove_approver.html.haml