Fixed AutoDataSwitchPreferenceControllerTest

The settings Flag is not assigned value, it cause test cases failed

Bug: 326543866
Test: have tested the v2/android-settings/apps/robolectric_settings_test at https://android-build.corp.google.com/builds/abtd/run/L92300030002155909
The test cases of com.android.settings.network.telephony are all passed.
Change-Id: I5a53fb6de741a7550f03ffca3c519d6b67c7c0fe
1 file changed