In `get_adjacent_post()`, `$excluded_terms` should check term_id rather than term_taxonom_id.

See #29663, #22112.
Built from https://develop.svn.wordpress.org/trunk@30263


git-svn-id: http://core.svn.wordpress.org/trunk@30263 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add tests for `get_adjacent_post_link()` wrappers.

Props MikeHansenMe.
See #29663.
Built from https://develop.svn.wordpress.org/trunk@30264


git-svn-id: http://core.svn.wordpress.org/trunk@30264 1a063a9b-81f0-0310-95a4-ce76da25c4cd