This aims to make the tests more discoverable and easier to expand.
Includes removing a basic test hidden among `get_pages()` tests, as there is already a more comprehensive set of tests available.
Follow-up to [1279/tests], [28399], [31338].
See #57841.
git-svn-id: https://develop.svn.wordpress.org/trunk@55590 602fd350-edb4-49c9-b593-d223f7449a82
