Revert "Add hidden API getDataSaverViaCmFlag() for CTS"

This reverts commit 9e87fc384a03c0091e19b58b63a495e83145c296.

Reason for revert: This change is not required now (aosp/2815393, aosp/2831370)

Change-Id: I77d5f3047f4f4ec656d6ba3d2c0781578572f8e4
diff --git a/core/java/android/net/NetworkStack.java b/core/java/android/net/NetworkStack.java
index 19ba6a1..dbb3127 100644
--- a/core/java/android/net/NetworkStack.java
+++ b/core/java/android/net/NetworkStack.java
@@ -23,7 +23,6 @@
 import android.os.IBinder;
 import android.os.ServiceManager;
 
-import com.android.net.flags.Flags;
 import com.android.net.module.util.PermissionUtils;
 /**
  * Constants and utilities for client code communicating with the network stack service.
@@ -104,16 +103,4 @@
             final @NonNull String... otherPermissions) {
         PermissionUtils.enforceNetworkStackPermissionOr(context, otherPermissions);
     }
-
-    /**
-     * Get setting of the "set_data_saver_via_cm" flag.
-     *
-     * @hide
-     */
-    // A workaround for aconfig. Currently, aconfig value read from platform and mainline code can
-    // be inconsistent. To avoid the problem, CTS for mainline code can get the flag value by this
-    // method.
-    public static boolean getDataSaverViaCmFlag() {
-        return Flags.setDataSaverViaCm();
-    }
 }