Add CTS for CarrierConfigManager public API.

KEY_ENABLE_BACKUP_CALL_ON_OPPORTUNISTIC_DATA_BOOL

Bug: 199121448
Test: atest CarrierConfigManagerTest
Change-Id: I09e09bfa4c1497027e09a4354d2dd18df6aae905
diff --git a/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java b/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java
index 4597a54..0c4b394 100644
--- a/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java
+++ b/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java
@@ -177,6 +177,11 @@
             assertEquals("KEY_USAGE_SETTING_INT doesn't match static default.",
                     config.getInt(CarrierConfigManager.KEY_CELLULAR_USAGE_SETTING_INT),
                             SubscriptionManager.USAGE_SETTING_UNKNOWN);
+            assertEquals("KEY_ENABLE_BACKUP_CALL_ON_OPPORTUNISTIC_DATA_BOOL"
+                    + " doesn't match static default.",
+                    config.getBoolean(
+                        CarrierConfigManager.KEY_ENABLE_BACKUP_CALL_ON_OPPORTUNISTIC_DATA_BOOL),
+                        false);
         }
 
         // These key should return default values if not customized.