Remove unused class ShadowKeyStore

Since the class android.security.KeyStore is going away, remove the
unused test utility class ShadowKeyStore that references it.

(ShadowKeyStore was originally used by a test, but
https://r.android.com/1353609 deleted that test.)

Bug: 326508120
Test: build
Flag: TEST_ONLY
Change-Id: I20f2330dee171a0bfe860a1318dc2f962a80bd19

tests/robotests/src/com/android/settings/testutils/shadow/ShadowKeyStore.java

@@ -1,43 +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 com.android.settings.testutils.shadow;
-
-import android.security.KeyStore;
-
-import org.robolectric.annotation.Implementation;
-import org.robolectric.annotation.Implements;
-import org.robolectric.annotation.Resetter;
-
-@Implements(KeyStore.class)
-public class ShadowKeyStore {
-
-    private static boolean sIsHardwareBacked;
-
-    @Resetter
-    public static void reset() {
-        sIsHardwareBacked = false;
-    }
-
-    @Implementation
-    protected boolean isHardwareBacked() {
-        return sIsHardwareBacked;
-    }
-
-    public static void setHardwareBacked(boolean hardwareBacked) {
-        sIsHardwareBacked = hardwareBacked;
-    }
-}