Move CLIENT_STICKY logic from client hide/unhide to group hide/unhide;

rationale being that clients should be able to hide/unhide independently
of group switching.

client.c

@@ -493,9 +493,6 @@ client_ptrsave(struct client_ctx *cc)
 void
 client_hide(struct client_ctx *cc)
 {
-	if (cc->flags & CLIENT_STICKY)
-		return;
-
 	XUnmapWindow(X_Dpy, cc->win);
 
 	cc->flags &= ~CLIENT_ACTIVE;
@@ -509,9 +506,6 @@ client_hide(struct client_ctx *cc)
 void
 client_unhide(struct client_ctx *cc)
 {
-	if (cc->flags & CLIENT_STICKY)
-		return;
-
 	XMapRaised(X_Dpy, cc->win);
 
 	cc->flags &= ~CLIENT_HIDDEN;