[Settings] Avoid re-create fragment when subscription not changed

Simply updating the content of fragment instead of re-create it in order
to improve the performance of mobile network page.

Bug: 149190278
Test: m RunSettingsRoboTests -j ROBOTEST_FILTER=MobileNetworkActivityTest
Change-Id: I744c2d76b814abdb619c8f40c3f113902ad8a827
1 file changed