Remove WifiNetworkScoreCache fake

Now that Robolectric supports O, maintaining this fake class is no
longer necessary.

Bug: 64262653
Test: n/a

Change-Id: I14d15720031ba70f83f81e8aff66681f44985704

tests/robotests/src/android/net/wifi/WifiNetworkScoreCache.java

@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2017 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package android.net.wifi;
-
-/**
- * Empty class def for {@link android.net.wifi.WifiNetworkScoreCache}.
- *
- * <p>Can be removed once Robolectric supports Android O.
- */
-public class WifiNetworkScoreCache {
-
-}