Route GsmCdmaPhone#exitEmergencyCallbackMode() to EmergencyStateTracker

TestSuite calls GsmCdmaPhone#exitEmergencyCallbackMode() for the next 922 call.
This call makes IMS service release ePDN.
However, EmergencyStateTracker and modem remain in ECBM state,
since EmergencyStateTracker doens't know whether exiting ECBM is requested
and it doesn't send EXIT_EMERGENCY_MODE request to modem.

When the next 922 call is triggered, modem is still in ECBM.
So modem gets the real network in limited service state leaving the
current network in normal service.

To make the modem exit ECBM, route the GsmCdmaPhone#exitEmergencyCallbackMode()
to EmergencyStateTracker.

Bug: 328668809
Test: atest GsmCdmaPhoneTest
Manual test steps
Step 1. Verify that a device is registered in the network.
Step 2. Start a 922 call from the UE.
Step 3. Wait for the 922 call to be ended from the network side.
Step 4. About 1 minutes after the 922 call is ended, exit the ECBM by manually.
Step 5. Make another 922 call.
Step 6. Wait for the 922 call to be ended from the network side.

Change-Id: Ie5da8efe814cf743b28d1f3a207a45c09ffd129a