In ApnEditor, restore preference values after re-creating.

After destroying and re-creating, the preference values in ApnEditor
are not restored. This results in incorrect behavior if it enters
two window mode where it's destroyed and re-created. The fix is to
have them restored and shown correctly.

Bug: 65338066
Test: Manual
Change-Id: I5ea16ce01c72061ab116f9c15bfc5cc39bb7a095