Trigger silent redial under alerting state

Silent redial is triggered only under dialing state.
But silent redial should also be triggered
under alerting state in some operators.

Test: atest ImsPhoneCallTrackerTest
Bug: 161450861

Signed-off-by: Sungjae <sung_jae.kim@samsung.com>
Change-Id: I13de4eff45c8ac2cc6c6adec02ecff8a6b26aee9