test: Remove python3.5 workaround in authproxy

Also, move the burden of checking for a timeout to the client and
disable the timeout on the server. This should avoid intermittent issues
in slow tests (for example mining_getblocktemplate_longpoll.py, or
feature_dbcrash.py), or possibly when the server is running slow (for
example in valgrind).  There shouldn't be any downside in tests caused
by a high rpcservertimeout.

test/functional/test_framework/authproxy.py

@@ -94,8 +94,7 @@ class AuthServiceProxy():
 
     def _request(self, method, path, postdata):
         '''
-        Do a HTTP request, with retry if we get disconnected (e.g. due to a timeout).
-        This is a workaround for https://bugs.python.org/issue3566 which is fixed in Python 3.5.
+        Do a HTTP request.
         '''
         headers = {'Host': self.__url.hostname,
                    'User-Agent': USER_AGENT,
@@ -106,24 +105,8 @@ class AuthServiceProxy():
             # TODO: Find out why the connection would disconnect occasionally and make it reusable on Windows
             # Avoid "ConnectionAbortedError: [WinError 10053] An established connection was aborted by the software in your host machine"
             self._set_conn()
-        try:
-            self.__conn.request(method, path, postdata, headers)
-            return self._get_response()
-        except (BrokenPipeError, ConnectionResetError):
-            # Python 3.5+ raises BrokenPipeError when the connection was reset
-            # ConnectionResetError happens on FreeBSD
-            self.__conn.close()
-            self.__conn.request(method, path, postdata, headers)
-            return self._get_response()
-        except OSError as e:
-            # Workaround for a bug on macOS. See https://bugs.python.org/issue33450
-            retry = '[Errno 41] Protocol wrong type for socket' in str(e)
-            if retry:
-                self.__conn.close()
-                self.__conn.request(method, path, postdata, headers)
-                return self._get_response()
-            else:
-                raise
+        self.__conn.request(method, path, postdata, headers)
+        return self._get_response()
 
     def get_request(self, *args, **argsn):
         AuthServiceProxy.__id_count += 1