Always respect the `setting.UI.ShowUserEmail` and `KeepEmailPrivate`
setting.
* It doesn't make sense to show user's own E-mail to themself.
* Always hide the E-mail if KeepEmailPrivate=true, then the user could
know how their profile page looks like for others.
* Revert the `setting.UI.ShowUserEmail` change from #4981 . This setting
is used to control the E-mail display, not only for the user list page.
ps: the incorrect `<div .../>` tag on the profile page has been fixed by
#23748 together, so this PR becomes simpler.
6706ac2a0f