Fix duplicate fields in logging example

[nchengyeeshen]

In some cases, logs will contain duplicate fields.

Here's an example.

{
    "level": "INFO",
    "msg": "request started",
    "ts": "Sat, 07 Jan 2023 02:15:16 UTC",  // Duplicate
    "req_id": "hostname/MlcrKoeXEN-000001",  // Duplicate
    "http_scheme": "http",
    "http_proto": "HTTP/1.1",
    "http_method": "GET",
    "remote_addr": "127.0.0.1:52572",
    "user_agent": "curl/7.85.0",
    "uri": "http://localhost:3333/",
    "ts": "Sat, 07 Jan 2023 02:15:16 UTC",  // Duplicate
    "req_id": "hostname/MlcrKoeXEN-000001"  // Duplicate
}

Since entry.Logger already contains all the fields we want to specify, there is no need to pass in logFields... again.

Here's the output after the change.

{
    "level": "INFO",
    "msg": "request started",
    "ts": "Sat, 07 Jan 2023 02:15:37 UTC",
    "req_id": "hostname/Hkbv1XUDxM-000001",
    "http_scheme": "http",
    "http_proto": "HTTP/1.1",
    "http_method": "GET",
    "remote_addr": "127.0.0.1:52581",
    "user_agent": "curl/7.85.0",
    "uri": "http://localhost:3333/"
}

[VojtechVitek]

LGTM