Only create the connection closed exception once (#9405)

(cherry picked from commit b96b01b)

aiohttp/client_reqrep.py

@@ -819,6 +819,9 @@ async def _on_headers_request_sent(
             await trace.send_request_headers(method, url, headers)
 
 
+_CONNECTION_CLOSED_EXCEPTION = ClientConnectionError("Connection closed")
+
+
 class ClientResponse(HeadersMixin):
 
     # Some of these attributes are None when created,
@@ -1178,7 +1181,7 @@ def _cleanup_writer(self) -> None:
     def _notify_content(self) -> None:
         content = self.content
         if content and content.exception() is None:
-            set_exception(content, ClientConnectionError("Connection closed"))
+            set_exception(content, _CONNECTION_CLOSED_EXCEPTION)
         self._released = True
 
     async def wait_for_close(self) -> None: