Revert "Tidy up new filter for disabling publicize on a post."

This reverts commit 8ed18b1eef0c2b9dfdbaab0d8efdfec05ce20b1c.
Revert "Add jetpack_no_publicize_post filter"

This reverts commit 4b741e2e702a2fb8ba14afa66a0f121e78ef3391.