Scripts: Add a missing date format to the `wp-date` config.

`wp-date` recently added the `datetimeAbbreviated` format, but the config wasn't sending it on page load.

Props pento.

Merges [43818] to trunk.

Fixes #45158.
Built from https://develop.svn.wordpress.org/trunk@44162


git-svn-id: https://core.svn.wordpress.org/trunk@43992 1a063a9b-81f0-0310-95a4-ce76da25c4cd