weaved: Use real webserver's request timeout value

Use the real request timeout value provided by web server now.

BUG: 23908251
Change-Id: Ic42d012a492cf3acaf846fc0852d07086e316c07
diff --git a/buffet/webserv_client.cc b/buffet/webserv_client.cc
index a66ed3f..154bc5f 100644
--- a/buffet/webserv_client.cc
+++ b/buffet/webserv_client.cc
@@ -136,9 +136,7 @@
 }
 
 base::TimeDelta WebServClient::GetRequestTimeout() const {
-  // TODO(avakulenko): obtain the timeout from web server.
-  // The current timeout is set to 1 minute.
-  return base::TimeDelta::FromSeconds(60);
+  return web_server_->GetDefaultRequestTimeout();
 }
 
 brillo::Blob WebServClient::GetHttpsCertificateFingerprint() const {