People sort order should be case-insensitve

To reproduce:

1. Visit the marketplace https://www.drupal.org/drupal-services
2. Pick an organisation e.g. https://www.drupal.org/nord-software
3. Click "X people Drupal.org" e.g. https://www.drupal.org/node/2808485/users

Actual result:

Usernames are shown in alphabetical order, case-sensitive. So usernames with capitalised initials are shown before those with lowercase initials. For example: "Kermit Zebra alpha porridge"

Expected result:

Usernames are shown in alphabetical order, case-insensitive. For example: "alpha Kermit porridge Zebra"

There's no useful reason to have case-sensitive sort. If I'm trying to find someone, I have to look twice, once in lower-case and again in upper-case. It's especially problematic for multi-paged views like https://www.drupal.org/node/1204416/users