Don't honor per-request timeout for now

This is a partial revert of #46869. Using a nondefault timeout fails
with:

```
  ▶ ERROR [expected OK] external/wpt/IndexedDB/idbindex-query-exception-order.html
  └   → WebDriverRun.run_func didn't set a result

Exception in thread Thread-4:
Traceback (most recent call last):
  File "/tmp/wpt/tools/webdriver/webdriver/transport.py", line 259, in _request
    previous_timeout = self._conn.gettimeout()
AttributeError: 'HTTPConnection' object has no attribute 'gettimeout'
```

... because `{get,set}timeout` are methods on `socket.socket`, not
`HTTP(S)Connection`.

tools/webdriver/webdriver/transport.py

@@ -204,8 +204,6 @@ def send(self,
             ``json.JSONEncoder`` unless specified.
         :param decoder: JSON decoder class, which defaults to
             ``json.JSONDecoder`` unless specified.
-        :param timeout: Optional timeout for the underlying socket. `None` will
-            retain the existing timeout.
         :param codec_kwargs: Surplus arguments passed on to `encoder`
             and `decoder` on construction.
 
@@ -233,7 +231,7 @@ def send(self,
         # runner thread. We use the boolean below to check for that and restart
         # the connection in that case.
         self._last_request_is_blocked = True
-        response = self._request(method, uri, payload, headers, timeout=timeout)
+        response = self._request(method, uri, payload, headers, timeout=None)
         self._last_request_is_blocked = False
         return Response.from_http(response, decoder=decoder, **codec_kwargs)