Privacy: Only show the Privacy Policy page notice when editing the page, not on drafts list.

Props chetan200891, xkon, garrett-eclipse.
Fixes #48431.
Built from https://develop.svn.wordpress.org/trunk@47284


git-svn-id: https://core.svn.wordpress.org/trunk@47084 1a063a9b-81f0-0310-95a4-ce76da25c4cd