Make default form display and display mode be first secondary tabs

Updated: Comment #0

Problem/Motivation

Noticed in #2193609: No page title on manage display & form for non-default view mode.

For content types (article) the default display mode (/admin/structure/types/manage/article/display) is first,
for account settings the default form display mode (/admin/config/people/accounts/form-display) and display mode (/admin/config/people/accounts/display) are not first.

Steps to reproduce

1. Install
2. Enable custom display settings for account settings.

Proposed resolution

Make default always be first.

Remaining tasks

User interface changes

API changes