Use android test_runner to run CtsWebView Hostside tests

Bug: 857590
Change-Id: I2e7387d87e0459e331648ddee8e106a0716af8de
Reviewed-on: https://chromium-review.googlesource.com/1144522Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Andrew Luo <aluo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577619}

android_webview/tools/cts_config/webview_cts_gcs_path.json

@@ -31,7 +31,8 @@
         "filename": "arm64/O/android-cts-arm_64-4666824.zip",
         "apkdir": "arm64/O/4666824/",
         "tests": [
-                {"android-cts/testcases/CtsWebkitTestCases.apk": ""}
+                {"android-cts/testcases/CtsWebkitTestCases.apk": ""},
+                {"android-cts/testcases/CtsWebViewStartupApp.apk": ""}
         ],
         "_origin": "aosp-oreo-cts-release@4666824"
     }