Fix the Wifi Calling back button goes to wrong screen

The Wifi Calling activitis had Settings as it's parent activity.
Remove the parent declaration to navigate Wifi Calling screen back
to previous activity or fragment correctly.

Bug: 111818398
Test: Manual
Change-Id: I95168785936aeea0740dbb8e26280eaa8417c015

AndroidManifest.xml

@@ -2883,8 +2883,7 @@
         <activity
             android:name="Settings$WifiCallingSettingsActivity"
             android:label="@string/wifi_calling_settings_title"
-            android:taskAffinity="com.android.settings"
-            android:parentActivityName="Settings">
+            android:taskAffinity="com.android.settings">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <action android:name="android.settings.WIFI_CALLING_SETTINGS" />