### 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
command.start()
        
        shown_ready = False
        while True:
            try:
                
                self.update_output()
                
                
                if not self.ready_time and self.is_ready():
                    self.ready_time = time.monotonic()
                if (
                    not shown_ready
                    and self.ready_time
                    and time.monotonic() - self.ready_time > self.ready_delay
                ):
                    self.print_ready()
                    shown_ready = True
                
                time.sleep(0.1)
            except KeyboardInterrupt:
                break
        
        self.print_output("standalone", "Shutting down components")
        for command in self.subcommands.values():
            command.stop()
        for command in self.subcommands.values():
            command.join()
        self.print_output("standalone", "Complete")
    def update_output(self):