### 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
"""
        Checks if the given job name is running and heartbeating correctly
        (used to tell if scheduler is alive)
        """
        recent = job.most_recent_job()
        if not recent:
            return False
        return recent.is_alive()
    def print_ready(self):
        """
        Prints the banner shown when Airflow is ready to go, with login
        details.
        """
        self.print_output("standalone", "")
        self.print_output("standalone", "Airflow is ready")
        if self.user_info["password"]:
            self.print_output(
                "standalone",
                f"Login with username: {self.user_info['username']}  password: {self.user_info['password']}",
            )
        self.print_output(
            "standalone",
            "Airflow Standalone is for development purposes only. Do not use this in production!",
        )
        self.print_output("standalone", "")
class SubCommand(threading.Thread):