Update icon for security settings.

- also fix the issue of dynamic tile icon is being cached and not
updated properly.

Change-Id: I9289260340c1cddc4123fda88c366d658a11ddfc
Fixes: 74255242
Test: visual

tests/robotests/src/com/android/settings/dashboard/DashboardFeatureProviderImplTest.java

@@ -297,7 +297,7 @@ public class DashboardFeatureProviderImplTest {
                 "content://com.android.settings/tile_icon");
         mImpl.bindIcon(preference, tile);
 
-        assertThat(tile.icon).isNotNull();
+        assertThat(preference.getIcon()).isNotNull();
     }
 
     @Test