Use -is:ignored predicate in dashboard queries

Now we have a specific predicate for finding ignored changes, we can use
that instead of the 'star:ignore' query.

Change-Id: I0c47fea273514a9117f20606d7202a6d1a153aa2

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/AccountDashboardScreen.java

@@ -101,7 +101,7 @@ public class AccountDashboardScreen extends Screen implements ChangeListScreen {
         + who
         + " -owner:"
         + who
-        + " -star:ignore) OR assignee:"
+        + " -is:ignored) OR assignee:"
         + who
         + ")";
   }