Remove data usage v1 code.

- remove all v1 code and the corresponding feature flag switch.

Bug: 117420679
Test: make RunSettingsRoboTests
Change-Id: Ib062c03c671b0f860698f5e5e153ab46d963175a
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 7689b11..f511278 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -2223,7 +2223,7 @@
                 <category android:name="android.intent.category.DEFAULT" />
             </intent-filter>
             <meta-data android:name="com.android.settings.FRAGMENT_CLASS"
-                       android:value="com.android.settings.datausage.DataUsageList" />
+                       android:value="com.android.settings.datausage.DataUsageListV2" />
         </activity>
 
         <activity