In [27108], #26903 was fixed, but only because we were using the example in the ticket, leaving out infinite depth for hierarchical taxonomies.
Adds unit tests, including `Tests_Term_getTerms::test_get_terms_seven_levels_deep()`.
Fixes#26903. Again.
git-svn-id: https://develop.svn.wordpress.org/trunk@27125 602fd350-edb4-49c9-b593-d223f7449a82