Add expectedIncorrectUsage flags for unit tests that generate invalid dates.

Since [29925], passing an invalid date to WP_Date_Query will generate a
_doing_it_wrong() notice. The current changeset adds the
`@expectedIncorrectUsage` flag to those existing unit tests that generate
invalid dates, such as those that test canonical redirect and is_404()
conditionals.

Fixes #25834.

git-svn-id: https://develop.svn.wordpress.org/trunk@29932 602fd350-edb4-49c9-b593-d223f7449a82