This page is slow to load which means:
- it’s annoying for us
- it’s potentially causing load on the database
This commit does two things to reduce the amount we’re unnecessarily
looking at this page:
1. Avoid redirecting to it when signing in as a platform admin user
2. Don’t go directly to it when clicking ‘platform admin’ at the top,
but instead show a holding page (there’s a fair chance you’ve clicked
that link in order to go and manage some email branding or find a
user, not wait for stats to load)