Update System default handler title on Bug report handler settings

- Replace "Android System (Shell)" with "Android System"
- https://screenshot.googleplex.com/U3pxUHx3Uv0
- https://screenshot.googleplex.com/qKqqZUJM2w6

Bug: 143017534
Test: Flash device and check the title
Change-Id: I3036520d5887f70d1c43896eda56587d2ff9cdab

src/com/android/settings/bugreporthandler/BugReportHandlerPicker.java

@@ -197,7 +197,7 @@ public class BugReportHandlerPicker extends DefaultAppPickerFragment {
                 return null;
             }
             if (BugReportHandlerUtil.SHELL_APP_PACKAGE.equals(packageItemInfo.packageName)) {
-                return mContext.getString(R.string.shell_app);
+                return mContext.getString(com.android.internal.R.string.android_system_label);
             }
             return super.loadLabel();
         }