Remove ProxyResolver from update_engine

Current ProxyResolver code only supports no-proxy. Therefore it is
barely any use. Remove current implementation for a better one.

Test: th
Bug: 235816007
Change-Id: Ieb46dedf6c6ea86b11c81d7691c2adb578d3d97d
diff --git a/mock_libcurl_http_fetcher.h b/mock_libcurl_http_fetcher.h
index a14f953..054d878 100644
--- a/mock_libcurl_http_fetcher.h
+++ b/mock_libcurl_http_fetcher.h
@@ -25,9 +25,8 @@
 
 class MockLibcurlHttpFetcher : public LibcurlHttpFetcher {
  public:
-  MockLibcurlHttpFetcher(ProxyResolver* proxy_resolver,
-                         HardwareInterface* hardware)
-      : LibcurlHttpFetcher(proxy_resolver, hardware) {}
+  MockLibcurlHttpFetcher(HardwareInterface* hardware)
+      : LibcurlHttpFetcher(hardware) {}
 
   MOCK_METHOD0(GetHttpResponseCode, void());
 };