Fixed that data connections not tearing down when APN set id changes

When APN set id changes (by changing the preferred APN in settings),
the existing data connections from previous APN set id should be
torn down. Fixed by checking the APN set id when building the
waiting APN list and tethering APN list.

Fix: 159761970
Test: DcTrackerTest
Change-Id: I9c18b88ccd9177fabc9f432c65fe777aa122fbd4