[Provider Model] Internal cleanup - remove Provider Model flag and deprecated legacy UI part.4

Test: atest NetworkDashboardFragmentTest
Bug: 197066557
Change-Id: I9781af3a53fe7050b414f0574abb7618f8d71707

src/com/android/settings/Utils.java

@@ -1230,8 +1230,4 @@ public final class Utils extends com.android.settingslib.Utils {
     public static int getHomepageIconColorHighlight(Context context) {
         return getColorAttrDefaultColor(context, android.R.attr.textColorSecondaryInverse);
     }
-
-    public static boolean isProviderModelEnabled(Context context) {
-        return FeatureFlagUtils.isEnabled(context, FeatureFlagUtils.SETTINGS_PROVIDER_MODEL);
-    }
 }