### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When attempting to sign some document using Localstack KMS inside a lambda container (also running on localstack), the localstack KMS listener returns some unknown error.

The KMS key and lambda containers have been created from the same CDK app deploy, and I can see all the resources in the localstack web console.

The test application I'm using to prove this behaviour is available here:
https://github.com/LukaHedt/localstack_kms_test

Instructions to run are in the main Readme, and the `/localstack/Readme.md` file.

`aws-sdk` returns an unknown error, and the localstack docker logs that I receive are available here:
https://pastebin.com/58Z3fXi3

Have done an amount of testing and can confidently claim the following:
- Have tested on multiple machines with the same outcome
- Doesn’t make a difference if I specify an ARN or a KeyID in the signing request
- Downgrading localstack versions either didn’t make a difference, or I couldn’t actually deploy a localstack container with version 0.12.20 or lower.

### Expected Behavior

KMS Sign should return a signature for the given payload.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

Test application demonstrating the current behaviour is available here:

https://github.com/LukaHedt/localstack_kms_test

Full instructions to run are in the `/localstack/Readme.md` file.


### Environment

```markdown
- OS: MacOS Monteray 12.3
- LocalStack: 0.14.0
```


### Anything else?

_No response_
"""
        Returns Localstack directory paths as they are defined within the container. Everything shared and writable
        lives in /var/lib/localstack or /tmp/localstack.
        :returns: Directories object
        """
        
        
        var_libs = (
            os.environ.get("CONTAINER_VAR_LIBS_FOLDER", "").strip()
            or "/var/lib/localstack/var_libs"
        )
        cache = os.environ.get("CONTAINER_CACHE_FOLDER", "").strip() or "/var/lib/localstack/cache"
        tmp = (
            os.environ.get("CONTAINER_TMP_FOLDER", "").strip() or "/tmp/localstack"
        )  
        data_dir = os.environ.get("CONTAINER_DATA_DIR_FOLDER", "").strip() or (
            DATA_DIR if in_docker() else "/tmp/localstack_data"
        )  
        return Directories(
            static_libs=INSTALL_DIR_INFRA,
            var_libs=var_libs,
            cache=cache,
            tmp=tmp,
            functions=HOST_TMP_FOLDER,  
            data=data_dir,
            config=None,  
            logs="/var/lib/localstack/logs",
            init="/docker-entrypoint-initaws.d",
        )
    def mkdirs(self):