In order to allow meta-related values of `orderby` to be handled properly,
the term query's `meta_query` object must run its `get_sql()` method before
`orderby` parsing.
Fixing this bug required addressing another bug in `WP_Meta_Query`, which
caused the table alias index not to be reset when calling `get_sql()`
multiple times on the same object.
Props littler.chicken.
Fixes#37151.
git-svn-id: https://develop.svn.wordpress.org/trunk@37860 602fd350-edb4-49c9-b593-d223f7449a82