Change ImsPhoneCallTracker to listen to the correct broadcast when

default dialer changed.

ImsPhoneCallTracker used to listen to protected broadcast ACTION_CHANGE_DEFAULT_DIALER
instead of ACTION_DEFAULT_DIALER_CHANGED. Fixed this to make
ImsPhoneCallTracker know the change of default dialer and prevent
untrusted app from setting mDefaultDialerUid.

Bug: 162741489
Test: Manually set default dialer to another app and check if
mDefaultDialerUid changed correspondingly by dumpsys.

Change-Id: I2335eb77b337454082f8c9db195fd8ecc4b2c72c