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/download_action_android_unittest.cc b/download_action_android_unittest.cc
index bef4342..968f875 100644
--- a/download_action_android_unittest.cc
+++ b/download_action_android_unittest.cc
@@ -37,7 +37,6 @@
 #include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/install_plan.h"
 #include "update_engine/payload_consumer/payload_constants.h"
-#include "update_engine/payload_generator/annotated_operation.h"
 #include "update_engine/payload_generator/payload_file.h"
 #include "update_engine/payload_generator/payload_signer.h"
 
@@ -70,8 +69,7 @@
       .WillRepeatedly(DoAll(SetArgPointee<1>(data), Return(true)));
 
   BootControlStub boot_control;
-  MockHttpFetcher* http_fetcher =
-      new MockHttpFetcher(data.data(), data.size(), nullptr);
+  MockHttpFetcher* http_fetcher = new MockHttpFetcher(data.data(), data.size());
   http_fetcher->set_delay(false);
   InstallPlan install_plan;
   auto& payload = install_plan.payloads.emplace_back();
@@ -139,8 +137,7 @@
       .WillRepeatedly(DoAll(SetArgPointee<1>(0), Return(true)));
 
   BootControlStub boot_control;
-  MockHttpFetcher* http_fetcher =
-      new MockHttpFetcher(data.data(), data.size(), nullptr);
+  MockHttpFetcher* http_fetcher = new MockHttpFetcher(data.data(), data.size());
   http_fetcher->set_delay(false);
   InstallPlan install_plan;
   auto& payload = install_plan.payloads.emplace_back();