### Apache Airflow version

2.2.3 (latest released)

### What happened

When I modify airflow.cfg about default webserver listening port to 8000,  then start with "airflow standalone"

A error will be printed:
 webserver | [2021-12-25 22:20:08 +0800] [16173] [ERROR] Connection in use: ('0.0.0.0', 8080)
 webserver | [2021-12-25 22:20:08 +0800] [16173] [ERROR] Retrying in 1 second.
 webserver | [2021-12-25 22:20:10 +0800] [16173] [ERROR] Connection in use: ('0.0.0.0', 8080)
 webserver | [2021-12-25 22:20:10 +0800] [16173] [ERROR] Retrying in 1 second.
 webserver | [2021-12-25 22:20:11 +0800] [16173] [ERROR] Connection in use: ('0.0.0.0', 8080)
 webserver | [2021-12-25 22:20:11 +0800] [16173] [ERROR] Retrying in 1 second.
 webserver | [2021-12-25 22:20:12 +0800] [16173] [ERROR] Connection in use: ('0.0.0.0', 8080)
 webserver | [2021-12-25 22:20:12 +0800] [16173] [ERROR] Retrying in 1 second.
 webserver | [2021-12-25 22:20:13 +0800] [16173] [ERROR] Connection in use: ('0.0.0.0', 8080)
 webserver | [2021-12-25 22:20:13 +0800] [16173] [ERROR] Retrying in 1 second.
 webserver | [2021-12-25 22:20:14 +0800] [16173] [ERROR] Can't connect to ('0.0.0.0', 8080)

Source code position,
https://github.com/apache/airflow/blob/main/airflow/cli/commands/standalone_command.py line 209, function is_ready
        return self.port_open(**8080**) and self.job_running(SchedulerJob) and self.job_running(TriggererJob)

force the port to 8080, it's wrong.

### What you expected to happen

_No response_

### How to reproduce

_No response_

### Operating System

All System

### Versions of Apache Airflow Providers

_No response_

### Deployment

Other

### Deployment details

_No response_

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

airflow/cli/commands/standalone_command.py
"""
    Thread that launches a process and then streams its output back to the main
    command. We use threads to avoid using select() and raw filehandles, and the
    complex logic that brings doing line buffering.
    """
    def __init__(self, parent, name: str, command: List[str], env: Dict[str, str]):
        super().__init__()
        self.parent = parent
        self.name = name
        self.command = command
        self.env = env
    def run(self):
        """Runs the actual process and captures it output to a queue"""
        self.process = subprocess.Popen(
            ["airflow"] + self.command,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            env=self.env,
        )
        for line in self.process.stdout:
            self.parent.output_queue.append((self.name, line))
    def stop(self):
        """Call to stop this process (and thus this thread)"""
        self.process.terminate()
standalone = StandaloneCommand.entrypoint