Do not generate copyable slices for Settings Search

Copyable slices is to provide user a quickly sub-text copying way on
Settings Search. Since we plan to remove all sub-text from Settings
Search, the copying feature is no longer available.

Therefore, we don't need to generate copyable slices in Settings
anymore.

Impact search result:
Build number, Phone number, Hardware version, Serial number and IMEI

Bug: 143118037
Test: visual and robotests
Change-Id: I81474aed994678c42d73cc59e169573880de1378

src/com/android/settings/deviceinfo/PhoneNumberPreferenceController.java

@@ -90,21 +90,6 @@ public class PhoneNumberPreferenceController extends BasePreferenceController {
         }
     }
 
-    @Override
-    public boolean isSliceable() {
-        return true;
-    }
-
-    @Override
-    public boolean isPublicSlice() {
-        return true;
-    }
-
-    @Override
-    public boolean isCopyableSlice() {
-        return true;
-    }
-
     @Override
     public boolean useDynamicSliceSummary() {
         return true;