Improve some `wp-admin/includes/class-wp-filesystem-*.php` docs for `@param`.

See #30799.

Built from https://develop.svn.wordpress.org/trunk@30978


git-svn-id: http://core.svn.wordpress.org/trunk@30964 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Improve some docs for `@param`. Remove an unneeded `$wpdb` global import.

See #30799.

Built from https://develop.svn.wordpress.org/trunk@30979


git-svn-id: http://core.svn.wordpress.org/trunk@30965 1a063a9b-81f0-0310-95a4-ce76da25c4cd