Use new preferredAPN URI avoiding onApnChanged() call with self-change

Solving the issue that setting preferred APN from GDCT triggers
back APN change event and force unnecessary data call disconnects
and setups.

The new URI is added in Telephony Provider so ContentObserver
callback (results in onApnChanged) will not be triggered.

Bug:5448858
Change-Id: I4c0bcf32cec69cf1d0a0430f7a27495b89e93625