ImsPhone: defer intial roaming state update

The intial roaming update was in constructor of ImsPhone. It's so early
that settings provider and carrier config may not be loaded. Hence
incorrect WFC mode was got and set. Now we defer intial roaming update
to ImsManager#updateWfcFeatureAndProvisionedValues, invoked on
EVENT_CARRIER_CONFIG_CHANGED

Bug: 31972897
Change-Id: Id7a14f2d4ff0c638c53bcf7bbae2468750581e06
diff --git a/src/java/com/android/internal/telephony/imsphone/ImsPhone.java b/src/java/com/android/internal/telephony/imsphone/ImsPhone.java
index 9e4a41c..edd2c9d 100644
--- a/src/java/com/android/internal/telephony/imsphone/ImsPhone.java
+++ b/src/java/com/android/internal/telephony/imsphone/ImsPhone.java
@@ -231,8 +231,8 @@
         updateDataServiceState();
 
         mDefaultPhone.registerForServiceStateChanged(this, EVENT_SERVICE_STATE_CHANGED, null);
-        // Force update roaming state
-        updateRoamingState(getCurrentRoaming());
+        // Force initial roaming state update later, on EVENT_CARRIER_CONFIG_CHANGED.
+        // Settings provider or CarrierConfig may not be loaded now.
     }
 
     //todo: get rid of this function. It is not needed since parentPhone obj never changes