Update hint texts of all entries

The design team discussed the ellipses at the end of the hint text of
our entries and, even though they are present in most mockups, it turned
out they don't like them, so remove them.

It also turned out they don't like the prefixes like "Enter" before it,
so remove those, too.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/977

js/ui/overview.js

@@ -104,7 +104,7 @@ class OverviewActor extends St.BoxLayout {
                in the search entry when no search is
                active; it should not exceed ~30
                characters. */
-            hint_text: _("Type to search…"),
+            hint_text: _('Type to search'),
             track_hover: true,
             can_focus: true,
         });