Refine the check restriction function in WifiEntryPreference

- Move checkRestrictionAndSetDisabled function from WifiEntryPreference to necessary child-classes to avoid impacting other child-classes such as SavedAccessPointsPreference.

- Avoid adding ShadowRestrictedPreference to the unnecessary test class.

Bug: 233871529
Test: manual test
make RunSettingsRoboTests

Change-Id: Ia2145401558b293b5f4eaa0860f83b7d3bbab548

src/com/android/settings/wifi/LongPressWifiEntryPreference.java

@@ -16,6 +16,7 @@
 package com.android.settings.wifi;
 
 import android.content.Context;
+import android.os.UserManager;
 
 import androidx.annotation.VisibleForTesting;
 import androidx.fragment.app.Fragment;
@@ -33,6 +34,7 @@ public class LongPressWifiEntryPreference extends WifiEntryPreference {
     public LongPressWifiEntryPreference(Context context, WifiEntry wifiEntry, Fragment fragment) {
         super(context, wifiEntry);
         mFragment = fragment;
+        checkRestrictionAndSetDisabled(UserManager.DISALLOW_ADD_WIFI_CONFIG);
     }
 
     @Override