Disable metered preference in details page if unable to change

Wifi networks that cannot change their metered preference (such as
suggested networks) should have their metered preference in the network
details page greyed out and unselectable.

Bug: 151159939
Test: manual - build and visual verification
Change-Id: I8507cd6f39bed5e32884fbf667dffb3f330d8b56

src/com/android/settings/wifi/details2/WifiMeteredPreferenceController2.java

@@ -49,6 +49,7 @@ public class WifiMeteredPreferenceController2 extends BasePreferenceController i
     public void updateState(Preference preference) {
         final DropDownPreference dropDownPreference = (DropDownPreference) preference;
         final int meteredOverride = getMeteredOverride();
+        preference.setSelectable(mWifiEntry.canSetMeteredChoice());
         dropDownPreference.setValue(Integer.toString(meteredOverride));
         updateSummary(dropDownPreference, meteredOverride);
     }