Fixed handover issue on connecting data connection

Frameworks was incorrectly handover a data connection
which is still in activating state. The data connection
does not have a valid network agent and link properties
does not qualify for handover.

Test: unit test
Bug: 144012909

Merged-In: Iea9e87d1c79762bc6f233e0de7af9184753656c0
Change-Id: Iea9e87d1c79762bc6f233e0de7af9184753656c0
(cherry picked from commit ce85ca8e)