Convert android.test.legacy to Android.bp

The use of `TARGET_BUILD_PDK` has been deprecated in aosp/1320119, so
additional checks can be removed.

The license metadata on dependencies of module android.test.legacy has
been cleaned up in aosp/2995877. Therefore, the license of
android.test.legacy can be directly declared as "Android-Apache-2.0".

Bug: 319031379
Test: m android.test.legacy
Change-Id: I034ddd4f690205393c0d8ae385b8ad6bea7c4e6e

test-legacy/Android.bp

@@ -0,0 +1,38 @@
+// Copyright (C) 2018 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 {
+    // See: http://go/android-license-faq
+    default_applicable_licenses: [
+        "Android-Apache-2.0",
+    ],
+}
+
+java_library {
+    name: "android.test.legacy",
+    sdk_version: "current",
+    libs: [
+        "android.test.mock.stubs",
+        "junit",
+    ],
+    static_libs: [
+        "android.test.base-minus-junit",
+        "android.test.runner-minus-junit",
+    ],
+    dist: {
+        targets: [
+            "sdk",
+        ],
+    },
+}