Show QS data saver info dialog until enabled

Currently the quick settings 'data saver' info dialog is
only shown once when the quick settings button is tapped,
regardless of whether the end user selects OK or cancel.

This commit changes the behaviour slightly where the feature
info will be displayed until the end user has actually enabled
the feature for the first time.

Bug: 153108714
Test: Manual
Change-Id: I0fb44fc388bc7dcf8ae35eb60c52c09ce0317828