Bulk load builtin project default profile images

Summary: Depends on D19221. Ref T13106. When we fall back to default profile images for projects, bulk load them instead of doing individual queries.

Test Plan: Saw local task drop from 199 queries to 151 queries with the same actual outcome. Saw custom and default profile images on the project list page.

Maniphest Tasks: T13106

Differential Revision: https://secure.phabricator.com/D19222