Themes: Correct closing tag for the "Enable auto-updates" button in the JS...

Themes: Correct closing tag for the "Enable auto-updates" button in the JS template for theme auto-update setting.

Follow-up to [48418].

See #50516.
Built from https://develop.svn.wordpress.org/trunk@48428


git-svn-id: https://core.svn.wordpress.org/trunk@48197 1a063a9b-81f0-0310-95a4-ce76da25c4cd