Remove `parent::footer()` in `Language_Pack_Upgrader_Skin::bulk_footer()` as it prints a closing div which is not needed.

props michalzuber.
fixes #28947.
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git-svn-id: http://core.svn.wordpress.org/trunk@29094 1a063a9b-81f0-0310-95a4-ce76da25c4cd