Users: After [42256], remove unnecessary double quotes around `first_name` and...

Users: After [42256], remove unnecessary double quotes around `first_name` and `last_name` properties.

See #42713.
Built from https://develop.svn.wordpress.org/trunk@42257


git-svn-id: https://core.svn.wordpress.org/trunk@42086 1a063a9b-81f0-0310-95a4-ce76da25c4cd