Use feature flag to show/hide AllInOneTetherSettings

This partially reverts commit 0ccc849de7
which added a config value. Instead, we will use feature flag to switch
between the fragments.

This CL also adds a postfix to keys in all_tether_prefs to
de-duplicate with keys in tether_prefs and wifi_tether_settings.

Bug: 148182953
Change-Id: I92832c786473990065a965409072e4117a7e75a8
Fix: 148618984
Test: make RunSettingsRoboTests
Test: make RunSettingsRoboTests ROBOTEST_FILTER=CodeInspectionTest

src/com/android/settings/wifi/tether/WifiTetherApBandPreferenceController.java

@@ -16,9 +16,12 @@
 
 package com.android.settings.wifi.tether;
 
+import static com.android.settings.AllInOneTetherSettings.DEDUP_POSTFIX;
+
 import android.content.Context;
 import android.content.res.Resources;
 import android.net.wifi.SoftApConfiguration;
+import android.util.FeatureFlagUtils;
 import android.util.Log;
 
 import androidx.annotation.VisibleForTesting;
@@ -26,6 +29,7 @@ import androidx.preference.ListPreference;
 import androidx.preference.Preference;
 
 import com.android.settings.R;
+import com.android.settings.core.FeatureFlags;
 
 public class WifiTetherApBandPreferenceController extends WifiTetherBasePreferenceController {
 
@@ -87,7 +91,8 @@ public class WifiTetherApBandPreferenceController extends WifiTetherBasePreferen
 
     @Override
     public String getPreferenceKey() {
-        return PREF_KEY;
+        return FeatureFlagUtils.isEnabled(mContext, FeatureFlags.TETHER_ALL_IN_ONE)
+                ? PREF_KEY + DEDUP_POSTFIX : PREF_KEY;
     }
 
     @Override