WPDB: Remove the addition of `STRICT_ALL_TABLES`, added in [30400]. This proved to be incompatible with too many plugins, as well as being incompatible with MySQL 5.7.

See #21212.


git-svn-id: https://develop.svn.wordpress.org/trunk@30587 602fd350-edb4-49c9-b593-d223f7449a82