When a variation product has an attribute with a value of "Any...",
and there's a filter by attribute widget for that attribute, then
that product won't be included in the counts displayed in the widget
(and if the count ends up being zero, the attribute won't be shown
in the widget).
This happens before since Woo 4.4, this widget works by looking at
entries in the term relationships table for varitions too
(used to do so for simple products and for "main" variable products
only), see PR #26260; but there are no such entries for
"Any..." attributes.
This commit fixes that by extending the SQL query used by the widget
to look for variations that have empty attribute values in the meta
table too.
a75da34a45