In wp_list_comments(), update the comment meta cache when the comments derive from WP_Query and the new ->comment_meta_cached prop is false.
wp_list_comments()
WP_Query
->comment_meta_cached
false
There are no uses of wp_list_comments() in Core where $comments are passed as the 2nd argument.
$comments
Adds unit tests.
Props wonderboymusic, bradt. Fixes #16894.