### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Starting localstack with the CLI `PROVIDER_OVERRIDE_SQS=asf bin/localstack --debug start` starts up correctly but then uses the `default` SQS provider.

### Expected Behavior

I would expect it to start the asf provider.

### How are you starting LocalStack?

With the `localstack` script

### Steps To Reproduce

* `PROVIDER_OVERRIDE_SQS=asf bin/localstack --debug start`
* `awslocal sqs create-queue --queue-name "test-queue"`

logs show:

```
2021-12-27T14:08:43.274:DEBUG:plugin.manager: instantiating plugin PluginSpec(localstack.aws.provider.sqs:default = <function sqs at 0x7f30e6d2b820>)
2021-12-27T14:08:43.274:DEBUG:plugin.manager: loading plugin localstack.aws.provider:sqs:default
2021-12-27T14:08:43.278:INFO:localstack.services.infra: Starting mock SQS service on http port 4566 ...
2021-12-27T14:08:43.279:INFO:localstack.services.infra: Starting mock SQS service on http port 4566 ...
2021-12-27T14:08:43.279:INFO:localstack.services.motoserver: starting moto server on http://0.0.0.0:38335
```

### Environment

```markdown
- OS: Ubuntu 20.04
- LocalStack: 13.2
```


### Anything else?

_No response_
"""Parses the environment variable $SERVICES with a comma-separated list of services
    and (optional) ports they should run on: 'service1:port1,service2,service3:port3'"""
    service_ports = os.environ.get("SERVICES", "").strip()
    if not service_ports:
        return DEFAULT_SERVICE_PORTS
    result = {}
    for service_port in re.split(r"\s*,\s*", service_ports):
        parts = re.split(r"[:=]", service_port)
        service = parts[0]
        key_upper = service.upper().replace("-", "_")
        port_env_name = "%s_PORT" % key_upper
        
        port_number = DEFAULT_SERVICE_PORTS.get(service)
        
        if os.environ.get(port_env_name):
            port_number = os.environ.get(port_env_name)
        
        if len(parts) > 1:
            port_number = int(parts[-1])
        
        try:
            port_number = int(port_number)
        except Exception:
            port_number = 0
        result[service] = port_number
    return result
def populate_configs(service_ports=None):