Invoke call cleanup on handover from GSM to IMS.

Previously we hung up the call which is problematic because the modem
maintains a single call list.  This would cause the IMS call to hangup.

Instead, we will not call a cleanup method on the call tracker.

Test: Manual
Bug: 63317180
Merged-In: I0b1710dd995398a4be6a9c346ccd434e565c47b7
Change-Id: I99accbcb83e02603048ed38ac084a3b5ffb22252
1 file changed