`CHAR` is redundant, since the `meta_value` column is `LONGTEXT`. Meanwhile,
use of `CAST()` causes MySQL to ignore any index that the administrator may
have added to the column.
A number of automated tests were doing searches for `CAST` in the SQL strings
generated by `WP_Meta_Query` (for reasons unrelated to the `CAST()` behavior).
These tests have been updated to expect the new query format.
Props ericlewis.
Fixes#36625.
git-svn-id: https://develop.svn.wordpress.org/trunk@37594 602fd350-edb4-49c9-b593-d223f7449a82
cb5b8479f0