refactor: GroupchatRoster: Fix revealing roster on first click

gajim/gtk/groupchat_roster.py

@@ -133,7 +133,6 @@ def do_unroot(self) -> None:
     def _hide_roster(self, hide_roster: bool, *args: Any) -> None:
         transition = Gtk.RevealerTransitionType.SLIDE_RIGHT
         if not hide_roster:
-            self.show()
             transition = Gtk.RevealerTransitionType.SLIDE_LEFT
 
         self.set_transition_type(transition)